* From Microsoft TechNet: We have tested DPM 2010 running in a Hyper-V Virtual environment and it is fully supported considering the following limitations, requirements.

1) The DPM storage pool disks cannot be .vhd's - they must be either iSCSI attached disks or Pass thru disks.

The following 4 types of disk configuration are supported as DPM storage pool in a Virtual machine.

A) Pass-through disk with host direct attached storage (DAS)
B) Pass-through FC LUN which is attached to host.
C) Pass-through iSCSI LUN which is attached to host.
D) iSCSI LUN which is attached to VM directly.

2) Item level restore for protected Virtual machines is not possible because that requires the Hyper-V role to be installed on the DPM server, but is not possible if Virtualized.
3) Short or Long term backup to tape will be limited to using iSCSI attached tape libraries, and we recommend a separate NIC for that connection.

Other than those limitations / restrictions, DPM runs fine in a VM.

As to your point #2 above: it is certainly possible to enable the Hyper-V role in a virtual machine. You just can't start any machines due to the lack of hardware support.
For ILR, do the affected VMs need to be started? Or just mounted?
If it's the former I can see that this won't work. If it's the latter, it should.

Hardware requirement:
CPU: min 1GHz, dual core, recommended 2.33 quard core
RAM: min 4GHz, recommended 8GHz
Storage pool: min 1.5 times the size of protected data, recommended 3 times.

For the DPM database, DPM 2010 requires a dedicated instance of the 64-bit or 32-bit version of SQL Server 2008, Enterprise or Standard Edition, with Service Pack 1 (SP1). During setup, you can select either to have DPM Setup install SQL Server 2008 SP1 on the DPM server, or you can specify that DPM use a remote instance of SQL Server.

If you decide to have DPM Setup install SQL Server 2008 SP1 on the DPM server, you are not required to provide a SQL Server 2008 license.

The installation guide is here http://technet.microsoft.com/en-us/library/ff399503.aspx