As for stability, the biggest mistake you can make imo is to go organized religion or theocracy and declare a religion. You have so many cities with diff religions it becomes a huge stability hit.
At the risk of pissing off Rhye:
Bright green is good, dark green is kinda bad, light yellow is bad and White is very bad. Don't ask for other ones or why they're colored like this. I just observe, then extrapolate.