The debates are basically going to be Obama saying ad nauseum, “You did the same thing, Mitt.”
The campaign is going to be one long dreary slog to the bottonm- with the least unpopular candidate after the mudfest emerging as the winner.
That depends. If SCOTUS strikes down Obamacare, Romney will have a huge card up his sleeve in that he'll always be able to answer, "at least what I did was constitutional" whenever the subject gets brought up.
If SCOTUS doesn't strike down Obamacare, yes, this charge becomes more difficult to defend against.