PvE Gambling in New Reno.
Gambling skill should not determine the possibility of winnning or loosing during gambling, but only ability to play at different tables/games. Max needed gambling skill could be cca 100 skill points and this skill could raise (to level 100) by using gambling tables or games. (if you dont want to add your own skill points). So in general, you dont need to tag gambling skill and gambling will be alternative minigame, you can test.
The possibility of win or loose during gambling should be set like in real world machines: cca 40 percent chance to win (=>60 percent chance that money will stay in gambling machine).
So your skill in gambling will only determine, if you can invest more money in different kind of gambling machines.
But i would also like possibility, that faction can rent, occupy, control, what ever, some casino and they could get reward from casino income. I can imagine situation, where in Junktown Don Gizmo casino will get as a reward for temporary time (one week) winner of hand to hand combat in local arena. Maybe the winner team could get all of the winning money in the casino (win - lose = reward). But because i think that this is too complicated, they can get only constant amount of money per one player who played in the gambling machine (of course, it has to be lower amount than minimal bet).
PvP trading card.. i will rather see very rare, random tragic card, that if you collect some of them, you can "use them" and this will give you small bonus in some skill, or perk. Lets players create their own "game" how to get different card, or let them barter this cards,... .