Using Open-E as backup server

Greetings.
I've been intermittently testing Open-E over the last year or so, thinking of using Open-E as a backup file server for hosting operations. We would have any number of VPS's, Dedicated Servers, and production servers connected.

Ideally I would like:
1) each client access to a share that is user/pass protected
2) each client restricted to X GB storage (quota)
3) each client NOT able to see other shares (Visible off right?)
4) an easy way to connect Open-E to my billing and admin panel so that shares, user/pass, quota, enable/disable can be done without manual setup.
5) the ability to mount as many as 100+ shares to a single system (CentOS 5.6) with each share mounted to the users home folders as backup (should be mount -t cifs....)

As well, what I'm wondering:
1) how will thousands of shares affect the network?
2) how many shares can a single "OS" (Specifically CentOS) mount reliably?
3) how will thousands of shares handle reboots, downtime? Will the shares automatically remount or will we have to go through and remount?

Anything I should know?

Thanks!