Really, all? That’s a mighty wide survey of the vast DB landscape. Yes, that’s a standing feature request.
The remote DC just needs to have a matching namespace name for the incoming shipments. For any namespace DC1 has with XDR enabled and DC2 as the target, DC2 needs to have a namespace with the same name. Other than that, their configuration can be completely different.
For example DC1 may be a production cluster with data on SSD, that ships a portion of its data (some sets) to a smaller analytics cluster. The analytics cluster can have less nodes, define the storage for the namespace to be in-memory, have replication factor of 1, and can add secondary indexes over the records. All that needs to match is the same name for the source and target namespace.