I just painted old cabinets in a house built in the 50s, with Valspar High Gloss/bright white, and the results are magnificent: I cleaned the cabinets (doors and drawers), sanded where it needed sanding, primed and applied 1 coat of this high gloss paint. It took 2 quarts, that's all.

As far as your other two questions, let the painting contractors on this forum advise you.