I have an 04, love it. It started out as a lease, ended up buying it out. I still get 25mpg average, and have modded the piss out of it so, it gets fairly good milage

Make sure you get the 3.8 not the 3.4. they usually get about the same mpg, but you'll be happier with the performance of the bigger engine.
Some dealers install aftermarket 6disc changers in the trunk as a dealer option, but generally it's just the single. I believe the newer style Imps have an AUX jack, but for about $20+ you can get a cheap RF modulator for your MP3 from radioshack/BB/CC tune your radio to xx.x and use your MP3 that way