Build quality is good. The RB is very strong and mod friendly.
Reliable depends how well maintainted it is and how far you push it. its a sliding scale.
if its near standard doens't need much more work than any other car. oil changes every 5,000ks with good oil etc....
Common problems, dont really know... make sure you get a compression/leakdown test before buying... don't pay any attention to km's on the clock most imports have been wound back.
Would you feel comfortable blowing ~40k on a car you've never seen or driven? i know i wouldn't, i'd prefer to buy local first, but if you can't find what you're after local you could look to import...
I drive my R33 GTR to work daily and track it on club track days without changing anything, drive on track, race drive home etc... but mine is pretty standard...
evo7 never driven one can't say sorry.
To give you some idea, stage 1 mods on a GTR includes exaust/cam gears/ecu/more boost on std turbos and you'll make about 250rwkw.