Battlestar Galactica Final Episode...WTF

OK, Scifi channel kept advertising that "all will be revealed" on the final episode. So what did it all mean? I get the opera house vision was explained, but what was up with the Baltar and Caprica 6 appearing before the real ones? WTF is Kara Thrace? WTF was that conversation about between Baltar and Caprica 6 at towards the end of the episode? Someone help!