This sounds pretty interesting. It also sounds like an idea I had, though it in a modern setting and you had to gather your cult and preparing for a global apocalypse. Once it happened, if you were right, people were more likely to come and join your group as survivors, and it was on a much smaller scale.
On that note, I think it would be interesting to have cultures that evolved in response to their environment and beliefs. So, a culture that has a belief that fire is bad and dangerous may have had a run-in with a fire god, causing them to want to worship more water-like things, and forbidding certain fire religions from their temples and meeting places (Or even the entire city or country, if enough people support the movement). A positive experience leads towards a preference, a negative one to a fear or hate - Or it could even have the opposite effect, making people decide to prefer something out of fear or a desire to use that weapon (Or whatever) against someone else.
Things like forbidding First Aid in a culture might be hard to put in, though, because you either go without or have some basic limits - Generally, it's like gimping yourself and your people for a silly reason. The reason that it would be complex is that it would only work if there were some way around it: You can't recieve first aid in combat, or it's alright to recieve magical healing. Either way, it'd take up more time and effort to program and implement to all skills so that it'd make sense with everything.
If you can do it, that'd be great, but I wouldn't stop playing (or looking forward to) the game if that feature didn't make it.
One thing, though: Keep it simple. Don't worry so much about the details that you'll burn yourself out. That happens to me a lot when I start working on a project - You seem to be able to keep your mind focused on what you want, though. Keep up the good work!