So from qs factory controller is preconfigured for 20s 72v battery? For fast test i could just plug and ride?
yes (for 72V controller) and yes
What if i build 22s battery, in settings i still enter 72v and for over voltage it would be 92.4(max charge)?
92V is not guaranteed to work with the mosfets and caps even though they are likely rated for 100V, you can risk blowing the controller
About connectors.
In throttle connector what is high brake and isdn?
there are no high brake and isdn in throttle connector, they are all separate connectors. High brake is battery voltage output to drive a full battery voltage light.
I think ISDN is output signal for speedometer
What is low brake, is it regen activates with ground?
yes
Reverse connects with ground to activate?
yes
In three speed connection what does parking do?
I guess throttle gives zero response, this pin is not wired in my controller, probably not in yours either. I think you need to look at wiring diagram on first page of thread "EM controller wiring.pdf" to see what i mean