Make sure you have upgraded the right storage resources and/or freed up enough space by consulting the "Statistics" section.
You will need to wait for the system to update the storage values, and only then will you be able to restore the service by clicking on "RESTORE SERVICE".
No, Cloud DBaaS does not let you downgrade resources.
No, Cloud DBaaS does not let you change the service.
No, Cloud DBaaS does not let you change the database.
No, Cloud DBaaS does not let you change the database version.
This happens when a database is deleted using the DBMS client and not via the Control Panel.
No, automatic backups will be kept for the next 7 days.
Manual backups will be kept until they are deleted manually.
No, the backups (whether automatic or manual) have no impact on the storage resource.