You certainly can. An MRC power pack is perfect for powering turnouts using the fixed AC output terminals for twin-coil switch machines or fixed DC for a Tortoise or other type of stall motor. For lighting, you can use any of the various outputs for incandescent bulbs as long as you don't overload the power pack or send too much voltage to the bulbs. For LEDs, use the DC outputs only, and make sure you have the polarity correct and the necessary resistors in the circuit.
The variable DC output can also be used for a Tortoise or lights provided you're not trying to also run your trains from those outputs.