2. the lower the wind the more agressive the motor and single is usually used for onroad and doubles and triples for off road.
3. A higher wind will be slower but less maintaince
4. The lower the wind the shorter the comm life
5. Gearing typends on the track and wind but a rule of thumb is the lower the wind the larger the Final Drive Ratio. e.g 7turn at 9.1:1 and a 19 turn at 6.5:1 for the same track.
6. Yes the Checkpoints get extremly good comm life same with the orion V2's.
7. 19T would be plenty fast and little maintainence
8. Most motors have them built in them
Try this Motor Tuning Secrets
Hope this helps