Can Windows NetBackup use iSCSI Tape drives

[Will_Restore]

Sure.  Check hardware compatability list for specifics.

https://www.veritas.com/support/en_US/article.TECH59978

[sdo]

Yes.  An example here:

https://vox.veritas.com/t5/Downloads/procedure-and-script-to-create-a-test-VTL/ta-p/810251