well im workin on a new early mod, and have been testing alot. to answer your question(s)

what I did was:
1) made map more historical
2) I beefed up the buildings & production capabilities
3) better quality and larger numbers of initial troops
4) beefed up rebels alot
5) made historically "rebellious" lands more rebel like
6) modded starting money to some extent

I think so far it has looked to stop the "any faction can conquer 1/2 the world by 1200 syndrome"

and when coupled with the patch, i think my adjustments will be even better, plus i will be using LK's new unit add on

so i cant wait =)