I hope this works out really well for you hamster. The only thing I'd say is to make sure the boundaries are clear.

Being dressed instead of in a bathroom, great idea. Cleaning his bathroom, no. Give him the supplies and leave it to him. By all means keep your areas clean and fresh.

He's not a guest, he's a tenant. Think along those lines. Some of your ideas are more based on the guest aspect than the tenant aspect.

I've never had good luck with roommates, but that's me. I hope, and I do think, this will work out well for you. Good luck.