How to set up backup for media files on Proxmox?

I am trying to set up a home server. Here is how I'm planning to do it:

/dev/nvme0n1 SSD, Proxmox, VMs & CTs
/dev/sda HDD, Media library
/dev/sdb HDD, Backup

I've installed Proxmox on the NVMe SSD and created a few VMs and CTs to play with.

I have also partitioned /dev/sda and created a ZFS partition on /dev/sda1, made a pool /pool and a datastore /pool/data.

I plan to put media files on /pool/data, bind mount it on a container and run Jellyfin to serve them.

I can schedule backup jobs for the VMs and CTs themselves on Proxmox, but I'm not sure how to backup the media files on /pool/data to /dev/sdb.

1. How would one go about setting up such backups? Do I need to setup something like a cronjob with rsync or is there some easier ready-made solution? Ideally it'd be something like Proxmox's VM backup jobs that let me prune and keep some copies daily / weekly / monthly / yearly.

2. What filesystem should I use for the backup drive / partition? Is there advantage of using ZFS to backup ZFS?

3. Can ZFS snapshots be used on /pool/data for additional protection? If so how do I set up, for example, automatic daily snapshots? Do snapshots take up little space if the files rarely change?

Thanks.