2) & 3) I really like these ideas. Especially the latter. Let's say they had some probability of either disbanding or turning. 4) "same bonus defending a stone fortress and a freshly settled pair of huts" -- If by stone fortress you mean a fortification, it already grants a fort aid bonus which works like the aid units give. 5) "Traveler's report: Mayan civilization wanders aimlessly into a jungle, gets lost and perishes." I think it's been suggested before and the answer was that they can't trust the AI not to commit suicide with something like this. 9) I think this would be a micromanagement nightmare. Remember how it was with slash and burn farms before, back when they degraded? Maintaining two was bothersome. Three was frustrating. And with four I gave up. This would be a hundred times that. A city just grew in population? Okay, time to find an idle worker and build an improvement. Epidemic reduces city population? Crap, the extra improvement is degrading again. Want to switch between a great food source and a great production source regularly (something the AI actually does for you fairly okay depending on what you're producing). Wake up the workers again.