Mysterious Grandmaster Moves

Help me try to fathom some of the mysterious moves from this game between super Grandmasters Motylev and Svidler from the Russian Team Championships.

1. I'm no expert on the Exchange Spanish, but 5..Qe7 in the below position looks an odd one to me, blocking the dark squared bishop in.

2. Check out the next diagram. Black played 9..Nh5 again an odd looking choice moving a piece twice before fully developed and placing a knight on the edge.

3. I've always been told that rooks want to be on open files. So it surprised me in the next diagram that white didn't play 12.Rad1, or even 12.Rfd1, but instead played 12.e5. I don't understand why?

4. In the next diagram, I'm not sure what black's best move is, but I don't really get the mysterious rook move 13..Re8.

5. Ok, I was just about ready to give up on chess when black chose to give up the exchange here with 16.Qxg5. Maybe it is good, but it certainly something I wouldn't do.

Can anyone shed some light on any of these mysterious moves?