sedna great point on #3. Stability needs tweaking.
I don't think we should return the huge penalties from RFC, in general we don't want civs collapsing unless conquered (or at least large portions of them being chopped away). It would be more realistic to increase the secession rate (it is already higher than in RFC). That way, of you conquer a large empire, simply the periphery would start to split.
It was always my understanding that the theory was of RFE was to watch as Europe develops over time and lead your civ to victory! In RFC this could be done with smaller empires, but with our map and number of civs it seems like we should be able to exist as stable empires with more cities in our core areas.
Of course stability would be hit with poor economies, over expansion to strange lands, bad civic combinations, unhealhtiness/unhappiness or too many wars.
Yes, civs should still collapse, but not if the civ is playing it "right".