Noob exhaust questions

Hey, I've been doing a little reading about different exhausts and there are a couple things I'm still confused about. (freak)

What's the difference between a resonator and a muffler?

If I decided to buy a CPE turbo back, would going with either the primary muffler, additional muffler, or both decrease the HP gains any appreciable amount?

I think I read that member Knowledge has a badass system. Did you get any/both additional mufflers?

If went with only one muffler which one would quiet the exhaust more, 12" oval or 6" quad core?

Mufflers and resonators and cats, oh my! Someone enlighten me!

For what I understand the mufler is what controls the noise level, and a resonator is used to produce a desired exhaust note. The resonator works by making sound waves "cancel each other out". Usually a resonator is a straight through design, while mufflers come in different shapes. A cpe turbo back already has mufflers, so why you want to add more?
If you are really concerned about noise level, you can add a glasspack to tone it down, or keep it stock.

Already has mufflers you say? This I did not know. It's just that I'm looking for max HP without letting the whole block know that I have max HP. Thanks for the input.