For gangs, I think there should be two separate parts of it. Your gang will be neutral once it starts. Basically, you can use that guild shop to choose what type of gang you want it to be. Tribe-Indians, Posse-Cowboys. You can still recruit Indians even if you are a posse if you like or vice-versa. After you choose what type of gang you are, you can only buy things from that part of the shop. If you want to switch, there would or wouldn't be a fee( your choice), but once you switch all your gang points will reset(not hours), and all your rewards will dissapear. If your gang is neutral, you can't use the shop yet.

Also, gang points shouldn't be rewarded just for basing. Perhaps gang events which reward you points if your gang wins and gang spars, every x amount of gang spars you win earns you x amount of points. Stuff like that.