1. Pretty darn fast and with the new SH. 28 even faster. Good times. I am thinking 3.5 g's to the tenth power.
2. The stock servos are OK but not awesome. 144oz of torque I think. They could for sure be worse. Get the most out of them and use a 6 volt receiver pack and not AA batts. Upgrade when you can.
3. www.cenracing.com is pretty darn good. This forum, the 1/8 buggies forum, read the reviews on the CEN site. Mucho info.
4. The older NX-26 engine was a pain in the arse to tune and keep a tune. The new SH .28 is a great engine and holds its tune well.
5. The answer is yellowish.

Good luck!