The equaliser was an optional upgrade totally independant of the rear speakers.
It you take the equaliser apart you are very unlikely to find further information other than what might be on a label externally. Taking apart would only be of use if you are electronically minded and can trace the circuit to find out what does what. However, you mention upgrading the stereo to a Pioneer CD. I suggest that this is likely to be of better quality than the equaliser anyway.
Equalisers where a simple way of getting better bass and treble control from an external unit in the days when these settings required a lot more circuitry. I would be more inclined to include a sub woofer if you really want to improve the stereo.
With regards to the rear speakers this will be a simple operation of extending the cables from your stereo under the carpets and into the rear. You can either follow the original pattern of putting in the side panels like so:
http://volcano.photobucket.com/albums/v ... kers_2.jpg
Or follow some others example of remaking the rear shelf and putting in there.