I don't think Sandoval would accept a SCOTUS nomination now, he likes being Governor. Perhaps he would closer to the end of his term, say mid-2017 or so, but definitely not now. And why would Kennedy require that his replacement be voted on by a Senate of the opposite party of the president?
Well, it would be his only real hope of getting a replacement who had similar views both on social issues and on the commerce clause.
I think I agree re: Sandoval. Collins would be the go-to nominee if a D president needs to confirm someone to a seat vacated by an R appointee. There would be additional pressure due to the tradition of confirming fellow senators and it would also give them a lean D special election. I think an R president would try the same thing with someone like Heitkamp if it was Ginsburg's seat and a D senate.