A. With Windows Server 2008 R2, you have CSVs that are volumes on shared storage (such as a LUN on a SAN) that are available to all nodes in the cluster simultaneously. Because the CSVs are available to all nodes simultaneously, you no longer have the problem of requiring one LUN for each VM to enable granular failover of VMs. (Prior to CSVs, a LUN was only visible to one node in a cluster at a time.) A single VM with VHDs available that are stored on different CSVs is fully supported. Because all the CSVs are accessible to all nodes, there's no problem with having VHDs stored on different CSVs connected to a single VM.
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