Clyde,
Sorry, I originally responded to the post, but it must've been somewhere else on the commuity portal, as I can't see my responses here. Again, the answers are:
1. Can be the multiple Altavault share with one cloud bucket?
No, each AltaVault share owns a cloud bucket.
2. Can be run a simultaneously back-up and restore in one cloud bucket using multiple Altavault?
No.
3. Will the 3 Altavault will detect all the files of each other?
No, each is independent of the others.
4. What is the Pros and Cons of this kind of setup?
You cannot run a multi-AltaVault connected environment (aka DFS type environment). Each AltaVault must be configured separately to the cloud and each cloud's contents are unique from one another.
5. It is possible to restore the back-up of the 1st site to the 2nd site or 3rd site?
Yes, but the AltaVault at each of the 2nd or 3rd site must be configured in disaster recovery mode (i.e. which means you cannot use it for backups from the 2nd or 3rd site).