1. Looks like the stock bar to me. The ones with the mesh are the Altia or GT-R front bars.
2. Whichever lip you like the look of. It's your car.
3. Again, whichever you like the look of. (Also, the "Nismo Aero" kit for the R34 is called the Altia kit)
4. Yes, Red badge for turbo, Blue for N/A, I believe.
5. I wouldn't go beyond 13-14 PSI.
6. Stock airbox is fine until you really start upping the power. If you must get a pod, go with Apexi.
7. Have a read here. http://www.sau.com.au/forums/topic/402597-r34-gtt-oil-change/
For the plugs, read here. http://www.sau.com.au/forums/topic/104405-spark-plugs/