Let's recap.
- You haven't played or bought GC2 yet.
- You don't even have a computer that can run GC2 (well, bootcamp or parallels, I guess...)
Yet you still want
a) a port of GC2 to a different OS, when it already has been announced that it won't be ported and that the upcoming 2.0 upgrade will be the last big release of anything GC2 related.
a multiplayer mode when there are several threads on the fact that it won't be even considered until GC3 with a huge sticky 'GalCiv - the case for no multiplayer' in the forums.
Fact is, it is highly unlikely that GC2, this late in it's cycle, will be ported to MacOS. You could have luck running it with bootcamp or parallels, though. Multiplayer, however, definitely won't be included. The above solution works less than more, since certain program routines aren't processed correctly and used over a long time can result in very strange behaviour.
GC2 is (proudly) one of the best single-player games currently on the market. If you're used to the Civ4 AI, with its huge cheating boni, you'll find the AI in GC2 a challenge in itself. And that is on mostly equal footing until you get to the really hard difficulty levels.