KVM backup and restore issues, and snapshot help please

First Part

Ok, so I have a KVM install on top of Ubuntu 14.04 which i manage remotely with Virt-manager.

I set up a 40GB LVM partition for a windows VM, and isntalled Windows on it. I then turned it off, and used dd to make a copy (with compression using gzip) to another partition on the drive called say vm1.gz. I was able to restore this fine.

I then did a load of work on the windows VM, and decided to create another backup. So i turned it off and repeated the backup, but gave it another name, so say vm2.gz.

When I tried to restore this backup, I got errors that there was insufficent space, and I noticed that the restored backup was 43GB, not 40GB, so larger than the LVM partition. How could that be?

I then deleted the LVM partition of the VM, and set up a new one at 45GB size, and tried to restore my backup to that. It again failed due to lack of space.

Dont know whats going wrong here?

Feels like a compression error. Next time i might back up without compression.

Second Part

Surely there must be a better way to backup my setup. Snapshots seem like the key. On my desktop I use Virtualbox, and you just click snapshot and thats it. If it goes wrong, delete the snapshot.

Is there a similar function for KVM and how do I do this easily?

Thanks in advance