My answer is no to all, let me explain now.
1. I recommend you not to PvP if you don't want to lose exp. If you choose to attack players then it is YOUR FAULT and if you lose
you will lose exp.
2. There have been suggestions about online battles.
3. If I PvP someone and that player is offline (the way it works right now) and I start using my inventory and chakra, I will have a
VERY BIG ADVANTAGE over the person I am versing.
4. Clan wars have already been suggested.
5. You will have to earn your turns by playing the game.