the standard headunit has a 6 disc changer in dash and a mini disc player, not a cassette player! Can be easily swapped out if needed. If you plan on upgrading this, try go for an altezza model that has the basic sound system, ie the one without the external amplifier. But i think most altezzas come with the "super live sound system" which has 8 speakers. Its easy to bypass the factory amp though with a lead you can buy on ebay.
Ive stuck in a Pioneer headunit, replaced all the speakers, new speaker wiring, 2 amps and a sub in mine!