Yes that’s good enough! Sorry I missed your statement about shutting down first. To clarify I leave mine running since a dump can recover if it gets corrupt.

Basically my backup contains the database and the SQL dump (or equivalent) - that way I don’t need to shutdown the service.

Most of the time that’s perfectly fine, but if the database were in the middle of an operation you risk corruption.

Individually. If the app requires a DB, I put it in the compose file. This simplifies both backups and migrations. My tooling for backups has a pre and post script I can customize on a per app basis so I just have the pre do whatever *dump for that DB and the post clean it up (backup takes a tar of the folder).