Raingoon, I liked your "enrgy barrels" and I think also the CIVilian concept is interesting.
I like when a model is clean and coherent with others part of game. I only have some dubt about your idea of a tolerant culture less able to attract people than some kind of fundamentalism.
I think it will have more effect on diplomacy with your neighboor (if you have intolerant culture none will love you - until has exactly same culture as you). Not very new (in SMAC a faction look better at you if it share same SE), but can be better developed with the help of your "culture" concept.
If Firaxis will implement some kind of "village to city" growth model with immigration (as already suggested into The List) your culture should influence how many people will join your civilization.
Anyway, good matter of discussion, Raingoon!
Adm.Naismith AKA mcostant