Preliminary unit list:

All factions will have access, in all provinces, to basic Spearmen, plus Archers, Crossbowmen, and gunpowder units, as well as Javelin-throwing cavalry shirmishers, and Peasants. Note that these units will not have the two morale points that were added for the expansion.
In addition, all Catholic factions will be able to produce Royal Bodyguards in all their provinces, unless stated otherwise, since this represents the local nobility. These units are 50% more expansive, man per man, than regular knights, so I think this provides a reasonable trade-off for the additional strength they provide. I may create a Royal Druzhina Bodyguard for the Russians with similar costs and availability. Also, unless specified, the Royal Bodyguard units are unchanged from the basic game.
This means that the restricted units are basically advanced spearmen, blades, polearms and non-royal cavalry, as well as faction specialties such as Longbowmen.

At this point, I have no plans to alter any of the Muslim units from the 1.84 version of the mod, except perhaps the return of some cavalry units to their original settings. Note that the Muslim factions will have a Homeland region as well.
Thus, I have listed below the units that will be restricted to each Christian faction's Homeland provinces, with mercenary suggestions where there are no native options.
Note that all non-regional Catholic units may be built in the Outremer (Palestine, Antioch and Tripoli). In addition, French units, which are used by the Crusader Kingdoms, may be built in Cyprus.

Current regionally restricted units such as Steppe Cav are implied to still be available as before, though this could change later on for a few such units.

New concept: Homelands. A dozen or so provinces that share the same ethnicity as a given faction, usually encompassing the faction's territory and some surrounding provinces. Note that two or more factions may claim the same province, where their peoples intermingle. This can often lead to conflict between the factions.

New concepts: restricted Inns and Buildable Mercenary units.
Inns can now be built only in provinces where the Mercenary "good" is found. These provinces will generally be in areas where ethnic Homelands overlap, and thus conflict is more likely, or in areas where special mercenary troops are available, such as in Ireland.
Each faction will generally have an Inn available at the start of the game. Thus, as your empire expands, you may be able to capture other designated provinces, build them up, and use them as further recruitment centers. However, this will take time and money.
Buildable mercenary units require all of the buildings that they would were they normal troops, in addition to the Inn, and may be built by any faction. These units cost 50% more than comparable units, just like Royal Bodyguards. They are a way of:
1)filling in the gaps certain factions have in their native troops, including Muslim factions
2)fielding balanced armies, or
3)just bulking up your forces, but all at a premium.
Note that Inns cost more to construct than before, since their potential effect is greater, especially for factions such as the Byzantines.

Generic buildable merc units (faction-specific units are specified in the faction unit lists below):
Alan Merc Cav- All eras
Germanic Knights- Feudal Kns; High and Late eras
Mercenary Viking Landsmenn- Early era only
Mercenary Gallowglasses- High and Late eras
Swiss Mercenary Pikemen- Late era only, Northern Europe
Almughavars- Late era only, Mediterranean region


Huns
The Huns have a hybrid force of both Eastern and Western unit types, which reflects their struggles against both Muslim and Christian forces.
Note: The Poles and Hungarians have lost the ability to launch Crusades that was added for v1 of the mod.

Early-
Hungarian Nobles- Feudal Kns.
Szekely Horsearchers- use VI stats
Bulgarian Brigands- bonus in Bulgaria
Woodsmen (regional)- Woodsmen now have a large shield and a little better descipline, which places them in between Urban Militia and Viking Landsmenn. Also, they can now be found all over Europe, except for the open Steppes, Italy and Iberia.

High-
Serbian Husars- Teutonic Sgts.; bonus in Serbia
Bashtina- Chiv. Kns.; buildable mercs
Transylvanian Archers- Arm. Ottoman Inf.
Croatian Spearmen- Chiv. Sgts.

Late-
Knights of the Banderium- Kns of Santiago
Clipeati- Pikemen
Armati Infantry- Halberdiers

Poles
The Poles are a somewhat hybrid force as well, though they develop some very nice heavy units in the last half of the medieval period, and are further strengthened in the Late era by their merger with Lithuania.
Note: The Poles and Hungarians have lost the ability to launch Crusades that was added for v1 of the mod.

Early-
Szekely Horsearchers- use VI stats; bonus in Moldavia
Polish Retainers
Baltic Infantry (regional)- Bulgarian Brigands; bonus in Novgorod
Woodsmen- bonus in Prussia

High-
Czeladz Bowmen- Mtd. X-bow w/Byzantine Cav. stats
Czeladz Lancers- Teutonic Sgts.
Knights of Dobrzyn- Kns. Templar
Polish Militia- Billmen
Silesian Spearmen- Chiv Sgts.

Late-
Rycerz- Kns. of Santiago
Rycerz Swordsmen- Hospitaller Ft. Kn.
Silesian Pikemen- Pikemen; bonus in Silesia

HRE
HRE units have lower than normal morale, though they do get a boost in the Late era from their unique ability to hire Landsknecht buildable mercenaries, from Inns located within their Homeland. In addition, their Homeland is larger than normal, encompassing the traditional HRE provinces, plus Livonia and parts of Poland and Hungary.
There are two Landsknecht units: Pikemen and Halberdiers.
These units have better than average morale, and impressive stats, so an integrated force, combined with the excellent German mounted units, can be a very potent army.
They *are* mercenaries, however, so they cost somewhat more than regular units, though less than typical mercs.

Early-
Dienstleuten- Mounted Sgts.
Knechte- Feudal Kns.; bonus in Bavaria (reflects seat of power)
Heerban- FMAA

High-
Teutonic Sgts.
Teutonic Kns.- Chiv Kns.; bonus in Prussia
Swabian Swordsmen- Swabia only
Teutonic Spearmen- Chiv. Sgts.

Late-
Gothic Kns.- bonus in Austria (reflects seat of power)
Gothic Ft. Kns.
Gothic Sgts.

Danes
The descendents of the Vikings remain strong in infantry, but weak in the other areas (spears and cavalry).

Royal Huscarles are the 40-man bodyguard unit for Danish nobility, and have early, high and late versions.

Early-
Viking Raider Cav- like VC
Viking Landsmenn- like VC; bonus in Norway
Viking Karlsmenn- orig. Byz. Inf.

High-
Nordic Mauraders- Mtd. Sgts.
Viking Huscarles- Hosp. Ft. Kns.

Late-
Mtd. Huscarles- lower-quality Gothic Kns.
Armoured Huscarles- JomsVikings

French
The French are somewhat the *default* faction, being the one that CA seems to have built the Catholic factions' unit lineup around. Well, I have managed to work in a couple of wrinkles which I think you will like.

The French bodyguard units are their era's knights, namely the Destriders, Chevaliers and Lancers. This means that those units are available for that era only, though the French nobility will lead impressive, 40-man units, reflecting French supremecy in mounted knighthood.
In addition, the French knights will still retain their bodyguard status, meaning they may be built in *all* French-controlled provinces.

The French, as well as the English, can obtain superior Flemish Pikemen from Flanders, should they be able to capture and hold that rebellious province.

Early-
Destriders- Feudal Kns.; bonus in Anjou
Feudal MAA
Urban Militia
Woodsmen
Pyrennese Brigands (sp?); Fyrdmen; regional; Catholic
High-
Chevaliers- Chiv. Kns.
Mtd. Sgts.
Militia Sgts.
Basque Inf.- Armoured Spearmen; regional; Catholic only

Late-
Lancers
Gendarmes- bonus in Paris
Compagnies d'Ordonnance- Hosp. Ft. Kns
Voulgiers- Halbs.
Partisans- Pikemen

English
The English develop potent archer units as the period progresses, get the unique Billman unit, and maintain adequate knights from their French possessions. Their native spear units are quite poor, however.

The English, as well as the French, can obtain Scottish Highlanders and/or Pikemen, with Highlanders available in all eras while Pikemen arrive in the High era. Though the Pikemen are of poorer quality than the regular unit that developed later, they, like Billmen, can be an advantage in the High era, and may be the only option available to the English in the Late era. In addition, Irish Bonnaghts (MM v2.04 stats) may be bought as buildable mercenaries.

Early-
Norman Knights- Feudal Kns.; bonus in Normandy
Norman Sgts.- Mtd. Sgts.
Woodsmen
Bonnaughts- Irish buildable mercenaries; Ireland only
Longbowmen
Fyrdmen- like VC

High-
Muntators- Sp. Jinettes
Welsh Longbowmen- Welsh Bandits w/bucklers
Billmen- bonus in Mercia
Gallowglasses- available in Northumbria and Scotland; bonus in Scotland.

Late-
Knights of Gascon- Chiv. Kns.
Hobilars- Sp. Jinettes+1; bonus in Ireland
Mercian Longbowmen- Sherwood Foresters w/bucklers

Spanish/Aragonese
When the Medieval period begins, the Christian factions have been pushed to the nothern highlands of the Iberian Peninsula by the Muslim invaders. The Early era covers the time when the Christians turned the tide of the war, the High era when the Almohad Empire collapsed due to losses and civil strife, and the Late era when the Christians set about consolidating their gains, including the initiation of the Inquisition, and the mopping up of the remaining Muslim-controlled areas.
The Sp/Ar enjoy a price discount on their units, and have stronger than average militia troops, as their people are used to defending their towns, and this war was about ethnic and cultural survival, rather than plunder or political aspirations.
Tercio units do not have a price discount, coming as they do after Spanish survival has been assured, but they do not have a price penalty, either, like Landsknechts.

Early-
Spanish Jinetes; bonus in Valencia
Kns. of Hidalgo- Feudal Kns.
Spanish Militia- Viking Landsmenn
Pyrennese Brigands (sp?); Fyrdmen; regional; Catholic only; bonus in Navarre

High-
Kns. Calatrava- Chiv. Kns.; bonus in Aragon
Caballeros- Teutonic Sgts.
Spanish Militia Sgts.- Viking Huscarles, can melee w/sh.
Basque Inf.- Armoured Spearmen; regional; Catholic only

Late-
Kns. of Santiago- bonus in Leon
Spanish Ft. Kns.- Hosp. Ft. Kns.
Tercio Pikemen- Swiss Pikemen

Italians
The Italians will be split between two factions; the Venetians and the Tuscan Confederacy. The Venetians will control Venice and all Italian provinces to the east, while the Tuscans will control everything west of Venice.
This will result in two relatively small factions, though ones with potent defensive troops and the potential to raise large armies through a profitable sea trade over time. The Venetians in particular could be poised to become a major power in the High era, when they will control Constantinople in addition to the normal Italian states.
Italian units are built to defend against attacks by their larger Christian neighbors, such as France and the HRE. This has lead to the development of superior spear units, and at an earlier era than other Catholic factions. Well-trained, versatile crossbow units are also a hallmark of Italian armies.
In addition, the constant skirmishes and outright wars among each other, along with the Lombards and Sicilians to the south, has resulted in Contadina and Popolo militias that are stronger than normal.
On the negative side, the urban nature of the Italian power structure, built more around trade than feudalism, means that Italian nobles have not attained nor kept pace with the martial prowess and technological development of their Catholic peers, though they do get some help with the arrival of Mercenary Hospitaller Knights in the Late era.

Early-
Italian Nobles- Feudal Kns.
Contadina Cav.- Mtd. Sgts. w/X-bows
Contadina Inf.- Militia Sgts.
Italian Sailors- Bul. Brigands w/X-bows; bonus in Genoa
Ital. Lt. Inf.- bonus in Milan

High-
Popolo Cav.- Teutonic Sgts.
Italian MAA- FMAA
Carraccio Guard- Varangian Guard
Popolo Inf.- Billmen; bonus in Tuscany
Pavise Sailors- Ital. Sailiors with pavise sh.
Pavisiers- Gothic Sgts.

Late-
Hosp Merc Kns.- buildable mercs; Chapterhouse required instead of Inn
Hosp. Ft. Kns.- buildable mercs; Chapterhouse required instead of Inn
Condoterri- Swiss Halberdiers; bonus in Rome
Pavisier Pikemen- Swiss Arm. Pikemen

Sicilians
The Sicilians have perhaps the most unique army in all of Christendom, in that it employs significant numbers of Muslim troops in its repertoire, as well as Italian units and Norman and Teutonic Knights.

Early-
Norman Kns.- Feudal Kns.; Malta, Sicily and Naples only
Berber Camel Warriors
Mamluk Horse Archers
Contadina Cav.- Mtd. Sgts. w/X-bows
Contadina Inf.- Militia Sgts.
Futuwwa
Nubian Spearmen

High-
Teutonic Kns.- Malta, Sicily and Naples only
Popolo Cav.- Teutonic Sgts.
Popolo Inf.- Billmen
Pavise Sailors- Bul. Brigands w/X-bows and Pavise Sh.
Murabitin Inf.

Late-
Hosp Merc Kns.- buildable mercs; Chapterhouse required
Hosp. Ft. Kns.- buildable mercs; Chapterhouse required
Almughavars (buildable merc)

Russians
The Russian forces change character with their subjugation by the Mongols. Before, they were modelled along similar lines to the Feudal Europeans, but after their forced vassalage, they gradually changed until they closely resembled the Steppe peoples they were primarily combating.
However, their western provinces do have the ability to produce western-style heavy infantry if it is needed to combat invading Teutonic Kns. or others.
Russian bodyguard units are 20-man Royal Druzhina Knights, which have separate variations for each era.
Note: Remember that the Steppes produce several types of cavalry which the Russians will have access to.

Early-
Boyars- unchanged
Woodsmen
Peshtsi- Slav Warriors; 100-man unit
Kop'ya Infantry- Feudal Sgts.

High-
Russian Retainers- Boyars w/ X-bow
Peshtsi Sgts.- Militia Sgts.
Rogatina Infantry- Rus Spearmen

Late-
Russian Dvors- Khazar Royal Cav w/axe
Cossacks- Teutonic Sgts.
Berdyshi- Halberdiers
Ratniki solva- Swiss Arm. Pikemen

Byzantines
The Byzantines are unique in the game for several reasons: the professional nature of their armed forces, the extent to which they used foreign mercenaries, their geographical location, and their history, such as how they begin the High era having lost their capital province to a deceitful combination of hypocritical Crusaders and schemeing trading rivals. Even though they were eventually able to recapture Constantinople, Byzantine power had been dealt a deadly blow, and the following years were simply the death throes of the empire.
Even though very capable units could have been raised or hired by the Byzantines, they were too crippled to make wide use of them. Though a start in the Early era gives you the opportunity to strike at your enemies before they can gain strength, later games will be a task of holding off the numerous aggressors around you, and then using your advanced units to grow your empire.
The Byzantines have access to perhaps more impressive units than any faction in the game, but they are hampered from raising large numbers of these troops by the geographic restrictions of many native units, and the mercenary status of the heaviest units, whose armour and training are foreign to the ways of the East.
To represent the large amounts of mercenaries in the Byzantine armies, they are given the ability to build Inns in three of their Homeland's provinces: Constantinople, Bulgaria and Greece.
Bulgaria and Greece were chosen because they are part of the Empire in all three eras, and to represent the fact that most mercenaries hired were fellow Christians from Europe.
Note that Constantinople is considered a European province.

The new, 20-man Kataphractoi bodyguards have added a bow and heavy lance to their already impressive arsenal. With upgraded armouries, they continue to be an effective unit for the duration of the Medieval period.

EARLY-
Kataphraktoi; bonus in Constan
Stratiotai- Byz. Lancers
Vardariots- Byz. Cav.
Hoplitai- Feudal Sgts. with an attack of 2; bonus in Greece
(Early) Varangian Guard- early only; buildable mercs; Constan only
Trebizond archers- bonus in Trebizond

HIGH-
Pronoiai Allagion- bonus in Nicaea; Asia Minor only
Kontaratoi- Italian Lt Inf. w/+1 attack
Paramonai- CMAA; Europe only
Mourtatoi- armoured Trebizonds, only available in certain coastal provinces

LATE-
Imperial Kavallarioi- Gothic Kns.; buildable mercs
Imperial Menavlatoi- Swiss Halberdiers; buildable mercs
Imperial Skutatoi- Swiss Pikemen; buildable mercs

Golden Horde
The Horde will retain their bonuses from the 1.85 version, plus they have some new units from their vast empire, and of course access to all the Steppe units.

High-
Mongol Heavy Cav.
Mongol HA
Mongol Warriors
Chinese Infantry- Saracen Inf.
Chinese Mangonels- w/exploding ammo ala gunpowder arty

Late-
Berdyshi- Halberdiers (from subjugated Steppe border provinces)
Ratniki solva- Swiss Arm. Pikemen (from subjugated Steppe border provinces)

This finishes up the major factions.

For the minor factions, I currently have:

Swiss, Late only;- Swiss units, Italian spear units, HRE and French infantry, Fr. and HRE Early-era Kns. and Mtd. Sgts. The Swiss are very strong in infantry, but weaker in mounted units than even the Italians. The Swiss have access to most infantry units of their three surrounding neighbors over the entire Homeland of those respective units. This means that the Swiss can potentially recruit troops from a very large area, but will this be enough to build an empire given their weakness in mounted units?

Ottoman and Seljuk Turks;- eras yet to be worked out. Both will use current Turkisk units.

Burgundians, Late;- Flemish Pikemen; French units

Papacy- Italian units

Lithuanians, Early and High eras (E&H);- Boyars for BD unit, Lith. Cav. instead of Polish Retainers, Polish units otherwise.
Livonians, Early only;- People of Novgorod. Russian and regional units.
Prussians, E&H;- Lith. Cav. BD, Polish units otherwise.
Teutonic Order, H&L;- Germanic units
Swedes, all eras;- Danish units
Scots, all eras;- Scottish units
Irish, Early only;- Irish units
Serbians, H&L;- Hungarian units
Kievans, E&H;- Russian units
Cumans, E&H;- regional units
Georgians, all eras;- Byzantine units
Cilician Armenians, all eras;- Byzantine units
Crusader Kingdoms, High era only;- French units plus Turcopoles
Tunisian Berbers, all eras;- regional units
Portuguese, and Basque, all eras;- Spanish units