Those are systemd services. You can see them with systemctl
Yes, several. However, they are mostly about flexibility. Snapper is a more advanced tool which provides more options at the cost of complexity. If timeshift meets all your needs, I wouldn’t worry about it.
If you are using the package btrfs-assistant-git you might want switch to btrfs-assistant unless you are interested in testing the next version because I just pushed new code that isn’t as well tested as the released version.
I just finished the next phase of development on BTRFS Assistant and it is ready for public testing.
Most of the changes are behind the scenes:
Significant code refactor to streamline and improve code and improve error handling
Added a configuration file to hold key values
Added more complete support for Btrfs maintenance which changed the layout of the UI and brought some new functionality
Made Btrfs maintenance an optional dependency
If you would like help with the testing effort, btrfs-assistant-git in the AUR will install the new version.
Please be careful with using this version on a production machine because the backend changes that were made could potentially have broken something I didn’t surface in my testing.