2 head units in 1 car?

[mafia29]

So, im only home for a few months, and my mom still drives the car and she loves her tapes, so basically my question is ....

i know the gen 3 95 camry came with the indash cd player, it came as a seperate unit....

1) would it have been attached to an aux?

2) Would it be possible then, to put in a new deck, and use it only for cd player function, by hooking it up to the stock deck, so i can run a sub to it?

3) I have a JBL 12" GTO1202D in a slot ported box. (which i want to also want to know, would it be better to put it into a sealed box?)

and im running it off of a JBL 260W 2-Channel Amplifier (GTO75.2II)

ive replaced the stock speakers , except for the tweeters, with Bose stock speakers from a RSX.

I want to run power to/from the new head unit for the sub and run the sound off the back speakers.

Is this situation possible?

Also,
if its not, i will just run the subs of the rear speakers anyways...
i know i need a hi/low ...
4) but how exactly do i go about doing this?