As far as the head unit goes...
I am just replacing an old Pioneer Premier deck with a Panasonic CQC-8400U. I don't know how it stacks up against your old Eclipse, but it seems to be pretty stellar and is now on sale @ Crutchfield for $250 as of this week.
http://www.crutchfield.com/S-uO4ct1Cr9Pm/cgi-bin/prodview.asp?I=133c8400&wm=cl
That's about the cheapest I've seen it.
I'm installing some aftermarket speakers today in my Legacy. I want to put them in the back, but from what I can tell, I have to take off the rear dash/deck to do so. How do I do this without breaking the rear dash? I've looked at all the possibilities so far, but nothing has worked yet. Thanks for any help you can give.