Darkmatter
Please check out the following links Link
This one will go to a program that was writen to help mod.
These next two are basics on how they work. Link Link
To answer shortly, none of what you want is moddable now.
You can however create new starting abilities, and pick them, which can give you more benefits, but the ai may pick them too.
Mods are currently 'limited' to adding/changing events (most often colonisation), UP votes (?), ships, political parties, techs, social improvements.