Is urbackup suitable for me?

office has linux server and a dozen windows 10 desktops.

i currently have a cygwin ssh server on windows. i use rsync to pull data from each desktop via ssh. snapshots+rotations on the server are done. great thing is a lot of space is preserved under normal circumstances. overall quite nasty to setup, and not native. manual work required in order to restore data

can urbackup do the same thing+rotations and also offer space savings?

is the setting up urbackup server onto zfs solely for offsite replication via zfs send+recv?

urbackup will do both, if client can autoregister if they re on the same lan than the server

Just try, but you should also save space.
You can do the rotations you want, look at the archive parameter and the keep min/max inc/full, ful/inc frequency, softquota

No, you can also use btrfs or whatever, each fs has his pro/cons. for space saving btrfs is the most advanced with urbackup.(personnaly i am not using it)
urbackup sever can also run on windows so it can also use ntfs