Is it possible to limit some technologies, civics and units to specific civilizations?

Thanks.

Yes it is.

Yes it is.

Haha, that's so mean. I think he was wondering how...

(I don't know, so ask TheLopez :p)

I started lookin at the XML files a bit and I would like to make separate tech trees for each civs, so a little input would be appreciated TheLopez. :)

Well, have you looked at any of the tutorials yet? That would be your best bet, IMHO.