One topic, it seems confirmed that Heyman will be on the Punk dvd(which sounds amazing!) as a talking head, I'm not sure about commentating on matches.
One big reason I think Brock came back is so he could fulfill his endorsement deals with Jimmy Johns, Deathclutch, etc. Unable to compete anymore in UFC, he would have lost tons of money on those deals. I'm sure Brock knew that as early as last summer as thus his extravagant WWE deal was born.