Firefox favourites you can easily export. So save that file somewhere, then replace the favourites file on the mac with that.
As for passwords, I've not looked at how it is handled on mac, keychain? dunno, but I'm assuming it uses the same setup cross-platform. Thus, take a look here http://snarfed.org/space/change%20firefox's%20saved%20passwords copy your passwords file over and voila. 🙂