Welcome!
1. I dont have a 32 GTR but Unigroup and Grey Imports look after my car. I have done a fair bit of track work and many driving/track events with mine and so far so good.
2. GTR's compared to say...late model type R JDM? (Prob better of using the term "import" or so here, unless you are on JDMST forums....) Then yes, it will cost more. Most people here will say budget another 8 - 10k for a 32GTR if its "cheap" because it may need to be rebuilt. They are getting on in age, and also the history comes into play.
3. Common problems - Im sure theres quite a few! If you have BIG hp - standard gearbox wont hold up after a while - and old member here went through 2 gearboxes with 370akwk
Oil pump?
Turbo's?
Compression etc
These need to be considered and checked if possible!
If its for the track, Duncan is the best man to speak with, same with T04GTR
Good luck mate!
Cheers!