First of all, Cantor's approval rating is underwater in Virginia itself. IIRC the number was something like 49-33 unfavorable. So forget helping Romney there.
I'd want to see that. I'd think he's not that well known outside of his district and the Beltway.
Agreed. But I think that people still want to believe it's true or will be scared to pass up the chance.
He's rock solid with the conservative base and commentariat (so are others under consideration, like Portman and McDonnell, but then people like Rubio and Martinez have their deviations or are untested) and loved by many of them for his fight, which the others haven't proven yet. His being Jewish is a novelty factor that could help in S. Florida as well, as well as piling up wasted votes in former NY-9 and parts of NJ with older Jews.