Replication is to avoid calls to other regions. If you have a full replica per region, that would be good. But I think you should set “replica=1 x Alphas”. Cuz if you have more than 1 (3, 5, 7), You would create N groups. Which in theory can be bad for latency across regions. Cuz a set of predicates could be “east” and other sets on the “west”. Unless there is a way to replicate groups that I’m not aware of. That way you could take advantage of sharding while having replication across regions.
Yep, that makes sense, but it is not possible as far as I know. Your cluster will rely on a single leader. No matter how much zeros you have appended.
The only way I see now is to use replica 1 x Alphas. (Your case is replica 7)