Pure Disk - OST Devices Question

hi

1. what is certified Pure Disk Device?
2. what can i do with a Certified Pure Disk Appliance?
3. what is the difference between a pure disk appliance and a OST Appliance?
4. do i need additional license or plugin on Puredisk - OST Appliance to use it with Backup Exec?
5. Can i share a Pure Disk Appliance over FC so all backup Exec Server Can Use it as deduplication storage? (all BE server use same LUN of Device)