Hi Ryan,
Welcome to SAU, and in particular the Stagea section! The stagea isn't going to be as easy as the evo, unfortunately. There are quite a few guys working on different ECU's around the place, but there isn't as much aftermarket support for VQ25det bits- compared to an Evo! But don't be discouraged. Plenty of guys have popped out good numbers without spending heaps, they really are a solid engine. (Jetwreck may well disagree at this point... )
As a wagon, Can't beat em! Thats why I got one!
I got no idea about the stereo, as I am a bit of the opposite, don't care too much. But depending on models, you might have the Bose stereo, which was an option on some cars.
Edit!- Phark... see what happens when you take a bit of time to reply, everyone else jumps in too!