BUG ads some sort of modular loading to the Civ4 Python, so that you don't have to fiddle around with the CvEventManager to merge things.
A tutorial can be found here. Not really difficult after you once understand it.
But don't let you put under pressure, I also normally don't provide separate BUG versions
.
Adding a normal CvEventManager to BUG will cause under certain circumstances (...no real idea) problems with the Python, so it's not advisable.
At the versions: BUG is the core. BAT is an art extension (no additional programming), BULL is a dll extension (no real further Python programming AFAIK), everything else (e.g. Better BAT AI) are combinations out of the others.
Programmingwise you really just have to care about BUG.
A tutorial can be found here. Not really difficult after you once understand it.
But don't let you put under pressure, I also normally don't provide separate BUG versions

Adding a normal CvEventManager to BUG will cause under certain circumstances (...no real idea) problems with the Python, so it's not advisable.
At the versions: BUG is the core. BAT is an art extension (no additional programming), BULL is a dll extension (no real further Python programming AFAIK), everything else (e.g. Better BAT AI) are combinations out of the others.
Programmingwise you really just have to care about BUG.