4) VM consistency
Can we say that all the imported VMs will be "crash consistent"?
I am not sure what you mean by "crash consistent", is it means "highly available" is oVirt language?
I mean in the similar state when you create a snapshot of a running VM, then clone the snapshot and then you use the clone as a backup of the VM itself
Yes, you can look at it this way.
Actually, you have "the same" VM but on the replicated domain.
It would be nice to have some sort of interaction between storage and oVirt, so that when in Active-Passive DR configuration, at least when you have to do a managed failover, you can interact with qemu-guest-agent of VMs and issue fsfreeze on Linux VMs and interact with VSS on Windows VMs.