A: You can export a flow as a package and import it into a different environment, or use it to restore the in the same environment at a later point in time.
C: The ability to make a copy of your flow is often useful when you want to create a flow similar to something you've already created. Or, if you want to maintain a draft of your working flow as you work on adding more functionality.
Here's how:
Go to your My flows page. Click on the More (...) menu item next to the flow that you want to create a copy of. Click on the Save As command.
Reference:
https://flow.microsoft.com/en-us/blog/import-export-bap-packages/
https://flow.microsoft.com/en-us/blog/make-a-copy/

Reference:
https://docs.microsoft.com/en-us/power-platform/admin/create-database
https://docs.microsoft.com/en-us/power-platform/admin/database-security