Nice! This looks pretty well thought out so maybe you have considered this already, but you should sort out how you want to handle your local laws surrounding hosting files and your culpability.

You will pretty quickly get nefarious and copyrighted material hosted on your servers, you will be asked by law enforcement for access and you will get DCMA take down requests, and scary sounding emails from lawyers.

Just engage a good lawyer, and check for any requirements local laws require you to fulfill pre-emptively.