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You need to know.
* DS switching voltage
* gate drive strength
* deadtime, if you need it
* min/max duty cycle and it´s acceptable shift.
* will the internal body diode become conductive? --> reverse recovery time
* ... and so on
Basically you found your best controlling frequency according your circuit and motor type and try with diffrent frequency. Generally 100khz to 300khz uses with this types of mosfets. The larger motor produce higher inductance, which forces a lower PWM frequency. So Datasheet will show only theoretical calculation.
This is very true, and it becomes less efficient and much more lossy as the frequency rises.
It does not just stop working at a particular frequency, so its not really possible to give a specific maximum.
Yes, the limitation is not usually the mosfet but rather the quality of the gate driver circuit, driving at 500kHz require more watts also than at 50kHz... having a low -Z driver is one of the problems that crops up most in power electronics design