1. Hammies are greedy and bread is like a big treat to them so they want to munch it quickly
...but they get hamster mix all the time so they don't get as excited
2. Hamsters shouldnt really be cleaned, they do most of the cleaning themselves, so I'd steer clear of that
3. He is probably nervous because of the fright due to the drop, if he deteriorates anymore in the next 24 hours, contact your vet x