It sounds like you'll need a set of tires (all four must be replaced at the same time to ensure they're within 1/32" to 2/32" of each other), a recirculating bypass valve (atmospheric-venting BOVs are known to cause a number of issues), and struts (lowering springs destroy stock struts... or better yet, ditch the lowering springs completely and go with another suspension setup).
I'd also switch up the intake.
Hopefully there is some type of "Stage 2" or protune on the car. That is pretty much necessary when running an aftermarket downpipe (part of the turbo back exhaust).
The other mods are ok.
The replaced valve cover gaskets are also a bit concerning.
Ask for a compression check.
It almost sounds like the previous owner has done just enough work to get the car in good enough shape to sell to an unsuspecting buyer. Dig a little deeper on that one to make sure that's not the case and if you're serious about buying it, use the above info as bargaining chips to get the price lower.
I've never sat in a wagon, so I can't comment on the interior.
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)