For your first question, the one about implementing a more traditional offense, that was not done for a few reasons. First, it is difficult to recruit talent to a system that you don't yet have on the field. Second, Michigan needed to make the transition eventually, and sometimes it is best to do these things like a band-aid. Third, to say that Michigan's players are better suited to the pro-style attack is something of a misnomer. Most of the skill positions were very young and, therefore, didn't have a great degree of practice in the pro style. The zone scheme for the lineman is very similar, as the blocking scheme for a zone stretch left out of the i form is fairly similar to the blocking for a zone read out of the shotgun single back. With Michigan unlikely to be this youthful again for many years, this year was a good opportunity to bite the bullet and make the transition.
As for your question about the six year deal, there is more to this than meets the eye. RR's deal has a substantial buyout for the first three seasons. That buyout diminishes greatly following third season. The general consensus on most major coaching hires is that they get three to four years (long enough to bring in "their" recruits") before termination becomes possible. The six year term benefits Michigan as much as RR, because if he is successful, his salary won't be jumping up on a yearly basis. Don't let the term fool you. RR has, at most, four years to put a big winner on the field. I think you're right to believe that he's up to the challenge.