What is going on with Sam in season 6?

Something is definately up with the Carpenters and even Sam is not aware of all of it - otherwise, why would they kidnap the female Djinn and not let Sam know they did it. What are they going to do with her and how many others might they be hiding and for what purpose? Also, they did not say who returned to Earth first - Sam or his grandfather? Was Sam released so he could counteract the grandfather or vice versa? If the other Campbells brought their grandfather back for some purpose; Sam may have been brought back to infiltrate and stop them. "why would Sam not take Dean up on the offer for the car?" - that is obvious. If Sam took Dean's car that would be admitting that Dean would never change his mind and join back up with him. The car is a constant reminder to Dean of what was and what could be again; and, he may need the car to join back up with Sam in the future. If Sam took it - well, out of sight, out of mind.

I saw this fanmade trailer that made me start thinking that the Sam we see may not be the real Sam, http://www.fanfiction.net/tv/Supernatural/ the mirror scene is well done, but it is made from bits from the previous season. The thing is it is possible, anything is possible in this show. PS Since Sam and Grandpa Campbell are back, I wonder if John is also lurking in the shadows somewhere.