Second Question: If Wall of Protection is up, does Complainers s/a regarding exchanging a Hero in Battle with a Hero in opponent's territory work?
As far as I know, if WOP is up on your side, then Complainers can only negate your special abilities.
Since we are talking about complainers, here's an additional question:
If a hero that has a special that is active outside of battle (e.g. Aaron's protection) and they have activated it in a previous battle, when complainers comes into battle at a later point, does his ability resets so he has to enter battle again to reactivate it or does it reactivate after the battle is over?