Damn, that is a downright steal! Need pics...for science.
Yeah, the big thing is the
strut tower rusting. Also check the timing belt if you haven't already. They're supposed to be replaced every 100k miles, so unless you're certain it was just done, that should be the top of your priority list behind the strut towers. If it snaps you'll quickly be in the market for a new ride again
The only other things that come to mind are
routine maintenance items (fuel filter, repacking/replacing bearings).
As for the stereo, unless you can snag one from a junkyard your money's probably best spent on a new head unit (even a cheap one) with bluetooth and such. OEM units go for way too much on eBay.
Tutorials are always welcome, look forward to seeing you around here!