Does anyone know the specs of the Mazda MP3 player... is it a hard drive based unit, or just a processor to play mp3's off the CD's??

What?

You should be able to find threads in the same forum you are posting from now, information such as... How to install, pictures, scanned factory instructions etc..

It's not a hard drive, the unit is made by Pioneer CDS-4077ZM, it reads MP3 encoded discs as well as normal CD music.