I generally clean resin parts with some good old plain dishwashing soap, in the kitchen sink, and gently scrub with an old toothbrush. Rinse well and allow to air dry. In the event of really stubborn mold release I may resort to Westey's Bleche White tire cleaner from the auto store.
If you have PollyPrep in your normal bag of tricks by all means use it. Do not let not having/using the material hold you back.
If there is a good solid undercoat between the resin and the Alclad, it should not be affected by either Future or MM differently than the same products on styrene.
Lacquer on resin may be more forgiving than lacquer on raw plastic. Hot lacquers may craze plastic but have little, if any, similar affects on resin