2- The Colts run defense was abysmal all regular season long, let's not kid ourselves. Easily one of the worst in league history.
(An interesting stat, brought to my attention courtesy of Pro Football Prospectus 2007: the 2006 Colts went 11-1 with Dallas Clark in the lineup, and 1-3 without him. Clark came back to the playoffs and they went 4-0, but of course the defense improved its play tremendously in that frame.)
3- Starters from last season who won't start this year: DT Anthony McFarland (given this weekend), LB Cato June, CB Nick Harper, and CB Jason David. The Colts already prepared themselves for the latter three.
4- About Peyton being neutralized because the defense can't get off the field: how was that not the case in 2006?
Manning took every single snap, in fact.