Replication director with Oracle

You may be able to make it work, but you seem to be over complicating the setup (just because you can doesn't mean you should).

IMHO I would simply perform Oracle agent based backups against the data guard copy of the database. 

If you really want to pursue the replication director approach, I would be talking with your DBA about how recovery can be performed to make sure that they can perfrom recovery from the snapshots. Then I would use the snapshots for short term recovery only without backing them up using NetBackup (do the agent based backup for longer term retention direct as suggested above). I would also be wary of developing a solution using Replication director (as this product is not really being developed further) - maybe see what CloudPoint provides for the NetApp array.

If you had a new model appliance I would also suggest you look into Oracle Co-Pilot, but I'm not sure the 5230 would cope (and is there sufficient capacity to allow an NFS share or shares to be presented to your Oracle servers). That said Co-Pilot is certainly supported on the 5230 as a platform.

As for how to configure the NetApp (NFS or iSCSI), I'd be looking at what Oracle supports. iSCSI may give you better performance, but I think NFS would provide greater scope for different solutions. 

Hope that helps