Re: question 1:
100g of curd is not going to have the same fat and protein as 100ml (roughly 100g, since milk is mostly water) of milk, because during the process of cheesemaking - cooking and draining the curd - whey is lost. Sure, right after the milk sets/coagulates - i.e. when the "curd" first forms - the amounts are the same as that of milk. But once the curd is cut, whey starts separating from the curd, and the cut curd particles shrink and dry out. The whey is mostly water, with some lactose and lactic acid, whey proteins, minerals/salts, and some fat. So as whey is expelled from the curd, the percentages of protein and fat increase.
For cow milk, about 80% of the protein is the casein types, that coagulate and stay in the cheese curd. The other 20% are whey proteins, which do not form bonds with other proteins, and leach out into the whey. So for a given volume of milk, the cheese curd roughly will have 80% of the milk's starting protein, the whey the other 20%.
Most of the fat will stay in the curd. However, the casein network of the curd can only hold so much fat, so with a really high-fat milk, or with a lot of added cream, or with rough and jagged cutting of the curd, some of the fat may be lost to the whey as well. Generally I wouldn't figure on much fat in the whey.
The final amounts of protein, fat, etc in a cheese are going to depend 1) on the fat percentage of milk (milk with more/less fat will make cheese with more/less fat relative to protein), and 2) on the moisture content of the cheese. A moisture cheese will have more water by weight, and so proportionately less protein and fat. E.g. a cheese like parmesan if very dry, maybe 1/4 water, while a washed-rind or bloomy-rind cheese may be 50-60% water. A parmesan is also made with skimmed milk, while the latter may use whole or even extra-cream added milk. So the parmesan is quite high in protein and low in fat compared to the other types.
Re: question 2
For cheesemakers making cheese often, consuming all the whey may get old... I wouldn't dump it though. True, can be drunk or consumed straight-up. Or used in baking to replace water (sometimes) of milk/buttermilk. Or used to water plants, added to compost piles, or fed to animals.