too bad, there is no all_restore_pre.sh
Thought the same, yet you need to mount the remote partition before you open the restore page so DirectAdmin can see the content and show the backup files for you to select.
A possible workaround would be to create a service and keep the partition mounted. You could even mount it as read-only to avoid possible data corruption on syncing the mounted partition. I also highly recommend avoiding writing through the FUSE system as it slows down the whole system and you won't be able to see the exit code and confirm the copy was successful other than reading the debug logs.
Yes, yet usually it's an old version, and since cloud storage API's still change way to often, I recommend using the installation script instead. Currently epel CentOS 7 rclone version is 1.47.0 while rclone latest version is 1.53.2 and the changelog between those two is huge: https://rclone.org/changelog/BTW rclone is available in epel
yum install rclone