IMO, you need to remove Romney from the equation if you want Santorum to go far. Take out Romney and Santorum likely benefits from a Santorum-Paul-Gingrich race. Perhaps if Paul wins NH, it will scare conservatives enough into supporting Santorum so he can win.
Hard to say who he's running mate would be (as in who would want that position). The obvious choice would be someone more mainstream, but it may be slim pickins' after people have more and more insight on Santorum's positions. Someone religious enough, but not as overly conservative as Santorum. Hmm, someone like Scott Walker could pair well. A moderate obviously would be best, but beggars can't be choosers.
Rick certainly gets hammered by Obama during the general election. The man is just too extreme and controversial to win. Depending on how hard he loses, the Religious Right will be hurt post-election. Obama wins somewhere around 2008 results is my guess.