1 : the cycles of backup program overwrites the old backups ? or it is incremented ?
Each backup is a full snapshot of MC. Each is written individually. You can choose how many backups you want to keep to save disk space. In the example above it is 8 backups shown in the "Retention count" option.
So if you backup daily you will always have the last 8 days snapshots available. If you backup hourly you will have the last 8 hours available.
Hope that is clear for you!
2 : for the restoration, example.
---- installs new-----
- a new blank installation of myC
- copy and create the directory /opt/backups/ with the backup in it, then launch : Settings-->Backup Restore
This restores the entire MC snapshot with all the settings and data preserved.