egads, i think you could write a book about this, honestly though if you have a Business Critical contract with symantec, i'd suggest seeing if you can get an EV Assurance done (project between NBU and EV BCE's to help create efficient backup and restoration policies specifically for EV)
Plus theres the NBU EV agents as well that make things a lot more simple.
Good starting place for best practice on backing up EV can be found here:
https://www-secure.symantec.com/connect/articles/enterprise-vault-backups-best-practice
The NBU + EV Agent stuff can be found here:
http://seer.entsupport.symantec.com/docs/340778.htm
What I would suggest against at all costs due to the headaches it causes for everyone is NOT to use NetBackup as tertiary storage and migrate EV CAB files to tape, its a one way road, is slow and whilst not technically causing any issues, it can be an administrative nightmare
https://www.linkedin.com/in/alex-allen-turl-07370146