Like Skippman said, you should get a Haynes manual just because. You can even get one used on EBAY for like $3 sometimes.
Just go to Dead Link Removed and they have tons of schematics for various cars. Sorry about your radio. I guess, however, if gives you incentive to buy an aftermarket with detachable face or something.
Certain issues with aftermarket head units now is that you won't need a harness for the head unit anymore, since they cut it at the wires (you'll have to splice). You will, however, most likely still need an amp bypass. The amp bypass comes with some wire harness adapter kits, so you'll still have to get one. If you buy from Crutchfield, they should give you that for free.
Jon