Primary vs. secondary weapons and other noob questions

[Darth Feather]

I downloaded this game from Steam and after getting a little bit of experience from getting a poor start as France in Vanilla (and I also played Shogun and M1 a long time ago), I'm starting an M2TW Crusades campaign with the Byzantine Empire. I have been reading totalwar.honga.net, FAUST, and this forum so I this time I can actually know what's going on. I had a few questions:

1. What is the significance of the primary or secondary weapons? If one is missile and one is melee this makes some sense in that one is used at range and the other in direct combat. Some mounted of mounted units have both the primary or secondary as melee and this a bit confusing. It seems like it would always whichever one is higher. If there both the primary and secondary attacks are melee, what determines when one gets used and at not the other (or both)?

2. Can a cavalry missile unit be ordered to melee attack? (Likely related to question #1)

3. What are the different levels of armor upgrade for a unit? Just to take one example, if you look at Trebizond Archers at honga.net it shows an armor upgrade as a leather tanner. Do Trebizond Archers benefit from any other upgrades further down the armor tech tree or is the tanner the only one? Likewise, Byzantine Cavalry is showing upgrades at both Blacksmith and Armorer, so does this then mean that any armor building more advanced than an armorer doesn't offer any benefit to Byzantine Cavalry?

4. Are the economic traits of your faction leader empire wide or only applicable to province to that he is stationed in?

5. Are the economic benefits of governors only in effect if there are in the town or castle?

6. How are retraining costs calculated? Does retraining only upgrade equipment (and possibly experience) or can it also replenish a unit's numbers back to full strength? It seems this is something I should know already, but in game I've seen retraining not put it back in full strength yet at the same time I thought I remember reading somewhere that this was how it was supposed to work.

1. Sometimes, one of their weapons is like Armor piercing, or cavalry who have a charge bonus when they use their lances. (hope I didn't misinterpret your question)

2. Yes, by holding alt and then attacking

3. That's it, you have a maximum armor on all of the units. When you right-click the unit card, you can see the next armor upgrade under the stats.

4. I am not certain, but there are certainly mods which make it that way.

5. Fairly certain they have to be stationed

6. yes it replenishes the numbers. If you don't have the appropriate barracks though, you can't replenish your numbers. For example, you can't make militia in castles. If they have for example a leather tanner in the castle you took with militia, you can upgrade the armor, but not retrain them (hope this makes sense)

Are your questions answered or am I completely wrong?

Welcome to the .org By the way.