Gambhir doesn't need any rest. He needs to get back in form, and quick-scoring form at that. Pandey is a good choice, but Vijay is a bit of a doubtful one.
The fielding has been a problem for the Indian team, even with a top fielding team in this tournament. You don't want liabilities like Munaf Patel out there.
Yusuf Pathan should play as a spinner and not as a batsman. When the team is looking to play an extra batsman, he should be an easy pick as a second spin option.
The 15th place should go to Ajinkya Rahane. In that dire IPL season 2 where no Indian scored more than two 50s, he was one of those who got two 50s and should be at par with the top Indian batsmen.