Check out ae64.com
The guy that runs that site sells harnesses that contain all the wires you need, recommends the steering wheel controls interface, and explains how to configure it as well as the various ins/outs of it. Really a good site.
I got the generic metra harness for mine, but had to hack into the factory wiring for steering wheel controls. I'd recommend spending the extra $5-$10 for the one from that site.
I got the apps 2 radio head unit from pioneer. I like it. I don't think you'll be disappointed with any after market head unit. Car audio does tend to be a slippery slope though . I'm doing my amp wiring for my sub shortly.