by Dominique Palumbo.
Hi,
related to backup you've all these capabilities :
Anonymise user data on backup
Backup courses
Backup sections
Backup for publishing on Moodle.net
Backup for import
Configure backup options
Download files from backup areas
Backup user data
Backup activities
I suppose that if you add Download files from backup areas capability (or mix some) to teacher role they'll be able to download backup.
Hope it's help.
Dominique.