First you need to understand mechnics a bit more. Motors have a max torque rating, we need to
figure out the torque, power and gear ratio required to perform the task.
First figure out the torque at the wheels - this depends on the wheel radius, max acceleration needed,
friction losses in the drivetrain/bearings/tyres, and the steepest slope that is needed to be climbed.
Given torque and speed you multiply them together to get power (use SI units everywhere, otherwise
its very easy to make conversion mistakes). Torque is newton-metres, angular velocity is radians/second,
power is watts.
Temperature isn't an issue for the motor, it definitely is an issue for the batteries.
The voltage is completely independent of the mechanical ratings, lower voltage means higher current
so in practice for high power you want larger voltages to prevent the leads being impractically thick.
The same basic motor is often available with different voltage windings, but identical mechanical specs.