My question: QPar to be used, I guess? Allow creation of new PAR2?
a) Yep, b) personal preference. Using "add files" in QP is hardly time consuming, and I don't want dozens of options in the right click explorer menu.
My Q: what is CPU?
Your processor. Set it to normal if you have a dual core processor, otherwise use Idle.
My Q: Should they be removed after a repair?
I personally don't. I tend to delete everything (rar's, par's and the actual download) once I've burnt and checked it.
My Q: To be enabled?
I wouldn't - repair automatically could be annoying if you're trying to do something else at the time. It's also hardly a bind to tick monitor when you want to use it.