I agree with csnow. Most alpines have mp3 read capability now. atleast the high end ones. you can find good prices at www.hookedontronics.com
i bought some stuff there and was pretty good. or you can get the 6 cd changer by alpine that reads mp3's and then hook that up to a regular alpine head unit as long as it's compatible with the mp3 changer.
as for the speakers try doing a search in the audio section for 300e speakers. there are tons of very helpful posts. I know since I did the search for mine and found eveything I wanted to find interms of info.
for wiring information you can visit www.the12volt.com
good luck !