Hi,
1 - During the backup process of virtual machines can it cause CPU, disk and memory stress?
Yes, but you can try local backups - https://learn.microsoft.com/en-us/azure/backup/backup-instant-restore-capability
Also check this -- https://medium.com/[@](/users/na/?userId=d0f16ba8-bffd-0003-0000-000000000000)_if/azure-backup-agent-slow-transfer-speeds-6726693c4477
2 - Does Azure Backup perform the process using snapshot without agents? Is there a need to use an agent in any situation?
AFAIK, no if you want to move snapshots to recovery vault
3 - During the process of sending the snapshot to the vault, can I start a restoration process using that recovery point that has already ended the snapshot or is it recommended to wait for it to end?
There won't be any problem if you want to use earlier recovery point with snapshot is already there in recovery vault