NH is Romney's primary residence. It's his home state since washed his hands of Massachusetts.
That won't have any effect on his chances in NH, primary or general. You don't really get a home state advantage unless you actually got elected statewide, so no matter where he lives, Massachusetts is still his home state de facto.
He's probably met a good number of the voters in the NH Republican primary. It's not a huge state. I wouldn't underestimate the appeal of having a President elected from the state of N.H. given how extremely unlikely it would be, absent Romney. He's had a compound on Lake Winnipesaukee for a long time and done yeoman's work building ties to the party.
