I replaced the radio in my 2004 a little while back, and also replaced the broken cup holder assembly. I remember removing the center trim piece was a pain in the butt, I needed a long screwdriver to remove the screws from behind the trim piece.
Once you successfully remove the center trim piece the radio is unscrewed and removed easily.
As far as wiring, with a $10 wiring harness adaptor you will not need to know what the various colors are, the color of the wires is standardized. Just match wire colors from your wiring harness adaptor to the radio.
Stew.