for above.. 2 speed is external , a derail of the chain between the cogs ..via a fork pushing the pulley sideways ..

Yes derailing must be on a rotating drive train while moving , not stationary .

there is some adjustment inside the left lever.. that shifts the 2 speed part.

the internal 3 speed can be shifted while stopped, its a epicyclic gear scheme..

BTW 2nd, N, is where the shifter chain is adjusted, 3rd is the default gear
It goes into that one when no cable is attached ..