Monsoon question.
Yes, you can still use your steering wheel controls if your new HU uses an infrared remote control. There are a few different adapters available. I like the PAC SWI-X
http://store.clubgp.com/catview.asp?catid=6
Sound Gate also makes adapters.
As far as the cd changer, it should work.
You can use your factory steering wheels with an aftermarket player.
You basically have two options.
1. Replace the factory with another factory
2. Replace the factory with a much nicer after market unit.

