A & C will work fine, a very good choice. The switch issues are unrelated to your power choice.
If you have 1122E switches, you will need 2 plastic fiber insulating pins in the correct locations for each switch to keep them from being actuated constantly(the one-year-only 1122 switch requires no fiber pins):
The left hand switch uses the same rails(the short, inside ones) in mirror orientation.
Also, using these in REMOTE mode, be sure not to let any part of the train park on those control rails(with the pins) of the switch while the transformer is plugged in as this will overheat the switch motors(solenoids).