Most likely, yes. Most devices has been manufactured with an idea that they will be used in areas where the supply power frequency is 50 or 60Hz.
Assuming that this question is about adapters for traveling to another country (not USA) then 230V is the equivalent of 220V. Just purchase a suitable adapter.
No! Normally not, the recistance in the windings is to hig on 60Hz and the pump motor has not power enough to work propelly. This happened to myself when I connected my Whirpool AWE 7519 to 230V 60Hz. Europian model for 50Hz.
no way because frequency cannot change
It is not advisable because the motor would run 20% faster which might produce damaging overpressure in the thermal circuit.
you can't
Yes, no problem.
230V/50Hz
220v 50Hz
nothing
There should be no problem at all.
220V , 50Hz
Not really because motors are designed to run at either 50 or 60 Hz and the wrong frequency might cause them to malfunction or overheat.