Roethlisberger is my go-to backup, and you won't lose too much if he has to fill in for Vick.
Chris Johnson is the pick that scares me, but only because I don't like the RB depth you assembled behind him. You have good WRs, but Chris Johnson and 3 rookies at RB screams mid-season waiver wire anguish, and 6-seed. These RBs COULD be strong when all is said and done, but other than Chris Johnson, I'd never feel confident about them. And if Johnson has another middling season, then you're in trouble. I think passing on David Wilson for Donald Brown in the late rounds would have been a better move, but only because he has nobody to push him for playing time in Indy, while Wilson has to contend with Ware for snaps, and a Bradshaw injury that may never come.
This is a good mock to see, because it answers some of my own questions and theories.