A few questions on gameplay (WWE 2K19)

WWE still can not make friends with the Russian language, and I still can not make friends with English. Because there are several unclear moments in gameplay. Please explain, this is not difficult.

1. Online. As in the selection of the game off created characters that would have been the only wrestlers created by the developers.
2. Pain. If the two types of pain. First, the one where the mini game is Put your stripes on stripes enemy, I understood. And second do not understand, what is there to do what is necessary, there is a circle, the right stick, the enemy moves, it expands, in General, is not clear.
3. What is this Payback? What kind of perks? If so, then how to apply them then?
4. Which mode is considered the main single? WWE'13 it was Attitude Era. WWE 2K14 - the 30 Years Of Wrestlemania, but here?