The speed should be no different for thesame motor.
A faster motor will need an ESC of higher Ampere output so that enough power can be supplied. If a fast motor is equipped with a ESC of small ampere, then there is not enough power to supply. The fast motor will be slow.
1. Theoretical, you are right.
2. The amount of current depends on the supply voltage and internal resistance of battery, esc and motor. Obey the simple ohm's law, I = V/R. As the internal resistance cannot be controlled, you can only control the current by adjusting the voltage. However, you cannot provide a voltage higher than the norminal 7.2V.