Exporting and importing a pool is a different operation. Ideally you can have both disks accessible at the same time in your system and you would replace the disk inside of the pool. I did this the other week in my NAS and it allowed the system to keep data integrity, but I had the room to have all disks active so it could resilver the disks.
If this is your only drive and you are fully swapping it out, then you are backing up your data and restoring it. This can be done manually, or using zfs send and receive
Kinda. You can copy your snapshots from @home too, meaning a restore from backup also restores your local file version history. There are also tools to push snapshots around as a large archive instead of dealing with smaller files directly.
The COW can also reduce the chances of running rsync on a large file that is currently being accessed, and getting a partial file in your backup. Or I suck at rsync 🤷♂️