Can I backup more than one server to a Virtual Storage account?
You can create multiple directories within your Virtual Storage account. As long as the backup software/program you are utilizing allows directory path specification, you can specify where to backup to, and therefore backup more than one server to your Virtual Storage account.

Can I run a FTP download site from my backup space?
Backup/Storage accounts are not meant for usage as heavy duty file servers or web servers to unknown/anonymous users. This service is meant to provide online storage for a limited amount of known/authenticated users. Certain features of the service may require authentication, possibly thru a VPN, in order to utilize that feature. There may be connection limits to the amount of users which are allowed to connect at one time, in order to limit abuse of the service by individuals attempting to utilize the generous diskspace and bandwidth levels provided with this service. Firewall rules may be in place to limit connectivity to certain pre-assigned networks, servers, or ip addresses. File sharing/download to known/authenticated users is permitted, within reasonable levels, as these policies and rules are in place only to protect the service from abuse, and usage that the service was not designed for.