Baltar is most def not a cylon. A very advanced human maybe, but not a cylon.
Remember the projection thing that the cylons do, i think that baltar can do it because he is the Cylon and possibly the human's Jesus.
But it will be interesting to see where earth is, i mean in reference to our time. Is it now (kinda like the OS coz they found earth in the '70's) or the future, or the past. Possibly its time lies somewhere adjacent to our own timeline.
The reason i believe the cylons are looking for earth is that they want to start the NC experiment again, but since ppl from the 13th tribe have never had any contact with the Cylons, the humans of earth my welcome the cylons with open arms.
Also is the beacon had a virus on it, then it is very possible that the virus still exists on earth, and still fatal to the cylons.
The Cylon god is either the old-man hybrid on the Razor flashback basestar or the a god from kobol the one that wished to be elevated above all others. It is also possible that the 13th tribe also worships the singular god, and its another reason why the cylons want to find earth.