Feeding a Parvo Survivor?
Youre doing fine, the pups stomach will get better. If youre concerned about nutrition, maybe try a liquid (ensure) or something similar and see how the puppy tolerates it. One week isnt bad. Also, Science Diet has some for sensitive stomach that may work.
Intact Male Cat Mounting Other Male Cat?
Mounting is not always a sign of mating. Often it is just a sign of dominance. The young one is trying to be the boss. Some of that is natural, but make sure he knows YOU are the boss.