You need to know someone from Datacenter, and you need to tell them for what kind of Storage will you use the servers, you need at least 4 servers at the start. And that's not everything, you need to modify File Host Script if you're using some pre-made. Basically, any location is good. Reason why you need to know someone from the Datacenter is that he can forward you the abuse emails from copyright organizations like DMCA.
Anyhow, if you grow you would need to register that File host in real life, and you would need to have your own Datacenter like HotFile,RapidShare & MegaUpload. I'd suggest you to not try to enter in File Host business. You would need to invest a lot of money, and you need knowledge. If you don't have knowledge, you need some more money to pay Developers and System Administrators to help you in maintaining of the File Host.
You need a short domain, and most of the short domains are registered in the '90s. So you would need to buy a domain too, which is easy to remember and professional.