It does not matter how many server you use. The backup has always to be installed on every system. I dont see a reason why the above script shall not work on multiserver systems.
1) The time required to restore a backup depends mostly on your hardware. If your hardware is able to load and uncompress the amount of data (which might be hundreds of gigabytes) in 10 minutes, then yes. Otherwise it will take longer.
2) See my link to the backup script above. Beside that, there are a lot of other backup solutions available for linux servers. There are also several tutorials available on howtoforge.