nice one.!

Yes, we can restore the backup from the Dr to 3 node cluster but make sure the version and application are same as DR setup.

This error will be coming if you have not given the proper permissions to the NFS folder please re-check the configuration once according to the backup guide if you still see the issue again please feel free to open a TAC case we are happy to assist ...

NO we should take backup locally the spaces allocated to DNAC is for internal purpose only and hence we should not take backup locally