[Serum]

1 yes, basicly it is. but this number gives you the amount of mass (torque) that can be moved in a certain time (rpm)
2 yeah, dead on, Ohms law; P(power)=U (voltage) x I (current) Current and voltage will vary; the voltage will drop under a higher load.
3 Yes, output power of the motor; the entire drivetrain will eat his share of power too. like 400watts on the motor, and 300 watts at the wheels (gears, bearings , time/energy it takes to get/keep parts moving)
4 in large lines; the lower the KV of the motor (from the same series) if they are wind at the same method (delta or wye) the lower KV will have more torque and can be geared taller. the 7700 can be geared lower with about the same poweroutput at the wheels.
5 this is something weird; A lower KV is usually ran at a higher voltage; if a high KV motor is used at 7V and should deliver 700watts, the current that's needed will be 100A, if the low KV motor runs at 10V, the 700 watts take 70A. (P=UxI)
6 Yes, The higher the voltage, the less the internal resistance becomes a factor. Thats why you can use aluminum as a conductor for high voltage long distance energy transport.