Hi,
Here are the answers:
1. The requirements from a licensing perspective are documented in the Data Fabric Solution for Cloud Backup Workflow guide, which describe the licensing requirements for ONTAP. Having a SnapVault license is fine, assuming you have ONTAP 9.1.
2. SnapCenter supports only NAS workloads to AltaVault today. VM and database workloads are coming in future releases.
3. That is correct . You do not want to replicate snapshots to cloud AltaVault over the WAN without encryption, which is not performed during the Snapshot replication.
Regards,
Christopher