Well,
1. For $11k you will have the exclusive option of a very stock R32 GTSt or GTS4 (GTS4 is the turbo 4WD). If you are willing to spend upto $17,000 you could look at all R32 and R33 Skylines with low to no mods.
2. Fuel consumption from the non GTR's is ok if the car is in stock form. 500kms from a tank on normal driving is not uncommon. If you are constantly giving it stick and are on the boost most of the time, expect half of that.
3. Nissan will stock what you need but at a hefty price, I have no experience with stock at wreckers but there is no shortage of after market parts for Skylines (Jap import).