I think that the closest era to this is rennaissance still glest is fantasy, plus there are more characters to develop then just those four, though that covers most of them, where would be a mix of europe and north america, woods, plains, mountains, clothing varies by faction, accent varies by region, what do you mean background?
I'm gonna make another topic to cover other stuff, this is a huge project and must be divided into itty bitty pieces, I'll update the timeline soon.