[Natasha95]

To answer your first question, Yes they seem to like pooping at the bottom of their cage. I have a 2.5-year-old dwarf hamster who was impossible to potty train, and she pees and poops all along the bottom layer of her substrate.

And as far as I know, hamsters stop eating when they're full, and they store a lot of food, so even if your hamster clears his bowl every night, he might be storing most of it. Just keep that in mind when you're deciding how much food to give him. As long as his diet is healthy, he shouldn't get overweight.

For the last question, even if your hamster seems tamed at first, once he gets used to his cage and it becomes his territory, you'll need to start the taming process all over again, so give him space for a few days and then start slowly reintroducing yourselves to him. Right now, everything's new and exciting for him (including your hands), and he'll need some time to settle down and find a routine.