The easiest way to swap out your radio would be to buy a
harness to hook up your new radio. And for your steering wheel controls to be converted to still work, you'll need this
adapter. The adapter transfers the signal from your steering wheel controls into and infrared signal, such as that coming from your remote.
I don't have a wiring diagram to send you, but I think jason-1995fbody has some in his gallery. You really shouldn't have to worry about messing with any factory amps to install a new head unit. Unless you do change out the factory speakers, then I would assume you would need to remove the amps. I still have my stock speakers (only because they still sound awesome), so I'm not completely sure as to whether or not you should leave the amps in if you change the speakers.