removing VM Checkpoint

hi

I have several VM's on hyperV 2008R2, managed with SCVMM 2K8R2.

there are several VM's with checkpoints that I want do remove those checkpoints because I don't need to use them anymore.

There are three doubts that I have:

1. If the VM has a fixed disk, can I just remove the checkpoint? is there any problem with the VM? Will it crash, if on-line?
2. If the VM has a dynamic disk, and the size of disk reported in SCVMM is smaller than the one that the VM is using, where is the remaining storage? is on the .avhd file? If so, what will happen if I remove the checkpoint?
3. in the end of removing the checkpoints, what will happen to .avhd files? will they be deleted in a "auto" way by the removing operation or do I need to remove them manually?

on this first picture you can see the fixed disk checkpoint. The second picture shows the gap between the storage reported on SCVMM and the OS report.

thank you all in advance