Concerning the turnover in coaching staff, and yes it happens more frequently as the team gets better, but a HC will try and stick replace with coaches who are similar in philosophy so there is less difficulty. Brewster not only changed coaches, but systems as well. The spread has seen its better days and needs some major tweaking, which Dunbar seemed unwilling to do. I think Brew needed to change it and to what it is, but it will take a little time for the players to catch up on everything. As for referring to going back to what Mason did with the offense, don't think he went all the way in that direction.
I am most excited to see what will happen with the OL and Davis. That is one of the big keys to success this year IMO. If the OL can open some wholes, the RBs, regardless of whether they are "power" backs or not, are going to pick up some yards.
Henderson would be a very nice commit, but he has not made up his mind yet. If he is concerned about being drafted, playing for MN does not prevent someone from going in the first round. And playing under Davis, who put a few in the first round at USC is only going to help.