To answer your question yes, you will need DNS or something to point the users to the DR site.
This is a great opportunity to place VMware on NetApp. With NetApp, SnapMirror and VMware running SRM this can be automated....and it works.
Is this a iSCSI, CIFS, NFS or FC install? Are there servers at the DR site? will you use the WAN for clients to connect to the DR site or is the plan to have the users at the DR site as well?
If you want to use a destination volume that was created for SnapMirror you have to "Quiesce" then "Break" the mirror. When you break the mirror it will mark the volume as read/write. Make sure you are using SnapDrive and/or SnapManager to initiate the snapshot and it will update the SnapMirror. You need to use these products to make sure the data has been quiesced from the applications perspective OR make sure there is no IO when you do your final SnapMirror update.