4 calsses 3 body types 2 factions, so thats 24 in total. and thief is kinda right, but correct me if im wrong in that you can only have a caertain amount of abilities, so you can't have them all. so that might be a problem in terms of class. but I'm sure 16 is enough for all your charcters, if it isn't im sure SD would give us more in a patch
you are right about the faction part, but I think each character has a resistance and security look, which is why when they say scars are permanent just like in real life, they mean it per that character.
The level cap is 20, so you get at least 20 abilities. They said at least 50 abilities, at another point they said if we have 100 and only 80 are fun, we'll ship with 80, so maybe they have 100 right now. I am guessing you get 20 per character + the "strongest" ones (Sense of Perspective, Battle Hardened, Combat Intuition, etc).