To remove the radio you have to take the console cover off which wraps around the steering wheel. its a little bit teadious but not to difficult. i dont remember the exact procedure. my radio is sitting in my garage i can take a look at it when i get home.
edit: there are no rca preouts. there are LOTS of unused pins in the back. since there was an amplified audio version you might be able to get preouts off the radio connector. if you are upgrading speakers and amps you might as well get a new receiver though too unless you just want to keep the factory look.