RAR is a different story, and I myself read through probably 50+ pages of forum threads to get a good understanding of what I was getting into.
Did you check
Colopedia of RaR?
We had put
lots of effort into explaining all our game concepts there.
Although it seems that effort was wasted because almost nobody reads it.
Some words about the mods from myself:
Overhauls:
AoDII: The first bigger Civ4Col Overhaul. Never really finished.
TAC: Focussed on improving and fixing issues of Vanilla. Probably the best mod, if you want to stay very close to the original game concepts.
RaR: Based on TAC but heavily expanding it with new features and game concepts. Still the biggest overhaul out there.
RaRE: ModMod of RaR. Still in work.
So basically you could draw those as a timeline:
(All of these mods used work and experiences of the mods before.)
AoDII -->
TAC -->
RaR -->
RaRE
TAC and
RaR were the only 2 projects that achieved to assemble really big Modding-Teams with more than 10 modders in their "Golden Ages".
(I was part of both projects in those days. First member of TAC and after TAC ended I became founding member of RaR.)
TAC and
RaR were both developed over several years and are probably the most stable Civ4:Col mods out there.
(They also have the biggest player communities considering Civ4:Col mods.)
I don't really know
RaRE, so I can't say how stable it is.
Conversions:
DoaNE: Although it stays in colonial scenario it completely changes many game concents and creates a very different gaming experience.
Medieval Colonization: Medieval Total Conversion. Lots of new features and concepts. Still in work.
Colonization 2071: SciFi Total Conversion. Never finished.
Werewolves: Total Conversion based on TAC that lets you defend your colonies against mythical werewolves. Quite solid and stable from what I have heard.