Are File Collections Saved In An Opus Backup?

Title pretty much says it all....

They are (as long as you check the right boxes when doing the backup).

https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Backing_up_and_Restoring_Preferences.htm

Excellent. Then would I be right to assume that the custom button I use to make a backup will include the miscellaneous data, because of the included "all" ?

Prefs BACKUP=all TO ****** Quiet

Yes, that's what the manual says "all" does with that command:

https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Prefs.htm

Thank you.