Box 1: Yes -
With VNet-to-VNet you can connect Virtual Networks in Azure across different regions.
Box 2: Yes -
Azure supports the following types of peering:
- Virtual network peering: Connect virtual networks within the same Azure region.
- Global virtual network peering: Connecting virtual networks across Azure regions.
Box 3: No -
The virtual networks you peer must have non-overlapping IP address spaces.
Reference:
https://azure.microsoft.com/en-us/blog/vnet-to-vnet-connecting-virtual-networks-in-azure-across-different-regions/
https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-manage-peering#requirements-and-constraints
