2 questions

[HunGeneral]

You seem to know what troops you can recruit with what governement, do you know this out of experience or can I find that info somewhere?

There is a usefull tool called "recruitment viewer" that should have been installed with EB - it allows you to see which faction can train what kind of units where (also what kind of barack is required) and also to see where a faction can build whta type of goverments... It is rather easy to use once you know how

I always try to build the highest governement possible (so I always try type I, if its impossible type II, otherwise type III, ...) is this a good idea?

Thats what I myself always do, but for historical roleplay you should make a gov III or IV in newly conquered provinces to reflect taht they don't becom part of your kingdom from one day to another. The other thing would be that in some provinces you can recruit quite usefull units which differ from your factional ones.

Taking a similar case for example: Makedon has homeland resource in two provinces north of Pella, however they can't train good quality phalangites there, however these provinces enable you to train Thraikioi Rhomphaiaphoroi (Elite Thracian Infantry) with the right regional baracks. These guys are wery usefull since they are great warriors with long AP (armour piercing) "swords" and can kill all kinds of enemies really fast (from Hellenes to Romans). Thereofre it would be better for Makedon to keep a type III govermnet in there for the better troops.

(As a sidenote: if you want you can build the regional baracks to max and then tear down the Type III goverment and build a higher one and you will still be able to train the same troops as long as the regional baracks are intact, however many consider this cheating so don't do it if possible...)

I hope this helps a little