Whey ricotta is quite a different beast from the fluffy white goop that's saturated the American market. Even packaged low-fat ricotta sold in most supermarkets is made from part-skim milk, not whey, and usually contains all kinds of wonky stabilizers to make up for the lack of fat. The process for making whey ricotta is basically the same as that for making whole-milk ricotta, except that you begin with fluid whey instead of fluid whole milk.
'whey' on Serious Eats
Making mozzarella at home is ridiculously easy, especially if you've got Kevlar hands. Mozzarella is a pasta-filata style of cheese which involves hand-stretching hot curds into pliable strands. Like pulling bread dough, the point is to manipulate it just enough to improve elasticity, but not so much as to toughen the thing.