1 & 2) You will adequate free space to get the merge process going. The following post answers part of your question.
What happens when I delete a snapshot? [Hyper-V] If you can figure out the sequence of VHD and AVHDs, the you can copy them on a separate disk and merge them using the process indicated in the
post I provided earlier. The you can replace the vhds and avhds in your VMs with the merged VHD. Backup is strongly advised before doing this. Infact do an export of VM before doing this.
Following are few post that might give insight on what you need to do.
Removing Old Snapshots from Hyper-V Query; Unfiinished Snapshot Merge Process! Proper way to delete 2008 Hyper V Snapshots Hyper-V Starting Server Mid Merge Hope that was helpful to you.
Regards,
Shahid
