Yup, your WRX complaints echoed mine. I rarely get that fuel smell, and when I do it's not particularly strong, but I live in socal so it doesn't often get that cold. Looking through my records it looks like the original owner took it in for that problem, but I don't see anything that specifically says whether or not it was fixed. Like I said I rarely get it, and then it's not particularly strong.
It's a complaint that's seen a lot of research in the WRX community. I'd say though, my BIGGEST complain, is the friggin clutch shudder. There was a TSB about that, and the original owner of my car took it in to get that fixed, but the dealer of course says they "can't replicate the problem." That's a bunch of BS, considering they had a service bulletin describing it, and an outlined fix. I'll be replacing the clutch soon myself.....not looking forward to it.
With regards to the leaning in cornering, boy did I notice that when I got the car. Upgrading the anti-swaybars isn't that big of a deal. It's the 2nd thing I did after upgrading the steering rack bushings to get rid of the memory steer. I upgrade the rear swaybar mounts, rear endlinks, and both front and rear bars to 24mm adjustables for less than $500. What a difference it made! Of course, wider wheels and better tires will also help tremendously with cornering grip, and a good spring/strut combo will do wonders to reduce body roll even more.
With regards to the turbo lag, look into a Cobb Accessport. Stage 1 is just an ECU reflash, helped a bit with the low end torque, brought the turbo spool a little lower in the RPM range, smoothed out the power curve. Running stage 2 is just great, but that requires a bit more work, though relatively simple. You should be able to find a used accessport for around $400 or so. Totally worth it, imo. But personally, if you're like me, you make it turn better first, then you make it go better.