I can't answer any of your questions, but whenever you decide to buy a convertable, or a car with a removable roof, you must either;
A. Garage it and only take it out in fine weather, or
B. When you view it, take it out in the rain!
I know that there are plenty of Targa Top cars that are prone to leaks, but I'm not sure if the NSX Targas' are reknowned for leaks. Maybe someone on here can let you know, or at least give you some indicators that you can look out for when you go viewing examples that you are looking at.
Happy NSX hunting ... I don't need to wish you happy driving should you buy an NSX ... if you're interested in owning an NSX ... happy driving is guaranteed!
Enjoy it while it lasts ...
Gone but never forgotten ...
'96 Black over Red 3.0 Manual JDM import (09/04 to 10/07)
'06 Grey Audi RS4 Saloon Manual (08/06 to 09/07)
'90 Lotus Carlton (06/05 to 08/06)
'77 Spitfire Mk V (06/87 to 09/89)