Vassal Questions (Cap, Factors, Civics, Tips)

[dragof2]

So I have been playing this mod for quite a while, and I've managed to scrape out UHV's for most of the civs (I really like this mod). Between tributaries and the overall benefit of not capturing cities in other's cores I really like picking up vassals. However, I don't really know much about the mechanics of what goes into the ai saying yes to being a vassal, I tend to be surprised by both yes's and no's.
1. Is there a cap on vassals? Does anything affect it? Generally 4 is the point that civs start saying no, no matter what. But sometimes I can do 5, and I've never been able to figure out how that works (and if I can go 6 or even higher).
2. What factors go into whether an ai will capitulate/vassalize? I do know that higher relative force is heavily weighted, but I don't know if stuff like what kind of civ it is (historical colonies more likely?), whether you share a religion, what age it is, what civ you are, ect. affects capitulation and by how much.
3. How do vassals affect civic upkeep? As nice as it is to vassalize Tibet to grab some resources and say you just grew your empire, it does seem to sometimes increase civic upkeep to making it not worth it. But civics like tributary encourage you to vassalize to make more commerce. Is there any kind of formula/factors for how a vassal will affect the civic upkeep of its master, so I can try and determine whether a vassal is worth having at all?
4. If anyone has any overall tips for general play with vassals I would greatly appreciate it, I am very much in the dark on a lot of this stuff.
Thanks

 

[Matara]

1.There's no limit. But as you get more vassals, your relation with other AIs will get worse (-2 penalty as "we're worried of our rivals being your vassals") , which makes it more difficult to vassalize peacefully. Also, when you're hitting the Domination Victory requirement by population or area, AI will tend to reject vassalize ("You've grown too powerful for us").
2.For peace vassals, you should have a strong army and keep good relation with them. It's easier to vassalize them if they're fighting a strong enemy, in which case vassalize will drop you into war. For capitulation, you should have a strong army and don't loss too much of them during war. Smaller and weaker AIs are more likely to capitulate. A huge russia is very unlikely to capitulate.
3.Vassal city population will count as your population when calculating civic upkeep. I'm not sure. But I think whether to vassalize mainly depends on your UHV requirements or just for fun.

 

[dragof2]

Thank you. I did do more testing, and have been pleasantly surprised to learn that if you are on sufficiently friendly terms with a civ when you declare war on them, then sometimes they'll actually ask you to vassalize them after if the war weakened them enough (Poland asked me 3 times when I was playing the HRE until I finally broke down. I should at least get them back on their feet before freeing them for UHV 3). It does look like there isn't a cap on vassals, but the your relationship does seem to affect any nation's willingness to capitulate/vassalize.

 

[Matara]

Yes. I think a friendly relation is a basic need for peace vassalization, unless they're seeking your military protection from an ongoing war. I got such vassals even in cautious or pleased relation.