Getting ready to upgrade

[Jester4kicks]

Ok, I am admittedly new at this. So couple questions.

First, in regards to the exhaust, what's the difference between an h-pipe and a cat-back system? Should I be concerned about the effect on my catalytic converter with either system?

Second, I can't find underdrive pulleys on macs website, only thing I've found is a balancer/harmonizer from steeda, and it claims to add 8-10 hp. Am I missing something?

Lastly, the custom chip I'm gonna have burned, I'm optimistic about the results cause the shop owner has his own dyno and seems to know what he's doing. But if I have to send it in for service, will removing the chip abruptly have an adverse effect on the engine?

ok, so I'm clueless about this stuff, can anyone bring me up to speed?