I don't know. But I do know he likely was a help in Clinton winning Virginia.
No. It didn't make a difference considering certain parts of VA that voted for Kaine/Obama in 2012 shifted away from Clinton. She would have won VA by a similar margin regardless of her VP choice.
To answer the question, I think choosing Kaine may have put off some of the more left-leaning voters who may have voted for Clinton if she chose a more progressive VP. However, I think a lot of those voters were never really on her side, to begin with.
