You can easily tell if it's all-wheel-drive by taking a look under the rear of the car and seeing if there is a rear differential... if you're not sure what one looks like then I wouldn't even be considering doing turbo installs or engine swaps. Swaps are fairly straightforward with Subarus, since they all use virtually the same chassis and engine design since the early 90's. Turbocharging our N/A engines isn't always a good idea, since they can't hold alot of boost in stock form, and our transmissions are crap.

 

Pay attention to the normal things you'd look/listen/feel for when buying a used car.. hard shifts, wheel bearing chatter, exhaust leaks, rust, burnt oil, etc.