Stereo suggestions, thoughts, ideas?

You need an amp with speaker level inputs that will use your existing speaker wires for amp inputs. you should be able to drive four speakers from there. I'm not an expert in this area but do know some. I would talk to an expert (like Crutchfield) before you invest money only to find it won't work together. This should work for what you are trying to do.
As far as speaker location, I did what you are talking about and it worked out great. You will need to do some homework on speaker size goes though because you have very little room to get it right.
Here's a link. On the last page is my install.

http://www.forabodiesonly.com/mopar/showthread.php?t=176535&page=2