I have a normal AM/FM radio right now. I picked up a factory CD/MP3 unit. Do I have to do anything special? Or can I just swap them?

Thanks For any help in advance......

You have to take the truck to the dealer and get the radio programmed for your truck. It can cost anywhere from nothing to 100$ so :(. Otherwise it fits right in.

what about an aftermarket cd player? can i just plug it right in?

I replaced the factory radio in my 07 canyon, and added Sirius. The only tricks are with the chimes and the antenna. If you get a deck from crutchfield, you will get everything needed except the chime box. That is an extra expense, but they do carry it. And unfortunately, the aftermarket harness is connected to that extra part.