1.)
Q: Can I get a CD Player to hook directly into the head unit?
A: Yes, now weather or not the head unit will control it is another story.
2.)
Q: Do they make units to make this happen?
A: You can get "translators" if your going to be replacing a factory installed CD changer or if the head unit supports it, to control the changer via the head unit. Thier expensive at around $110 for a cheap one. Your best bet if your not going to replace the factory head unit is to get one that hooks up using RF Modulation. Since it hooks up that way you will not need a translator. Those piggy back into the Antenna lead and you get to the CD Changer by "tuning" it in, like it was a radio station. Mind you theres going to be audio quality loss, but it will work, and be cheap. Control will likely occur via a remote control of some kind.
3.)
Q: Does the head unit have Pre-Amp outs?
A: Not likely. I will go on record as saying no. While the leads from the head unit run to an "amp" I would not consider them PreAmps for 2 reasons. One, because it's not an RCA style connection, which most amps are. And two, because the voltages supplied by the head unit are not on par with those of preamps. Mind you most cheaper amps like Rockford Fosgate will allow you to use these leads as PreAmps, do not confuse the two.
