AppleTV 1 (silver) Crystalbuntu on clear hard disk

Hello all, I'm thinking to install crystalbuntu on my apple tv 1g and I would like to know some help hints.
1) How can I bakcup a full image backup of the original hard disk with apple os installed?
2) Can I just install a new hard drive (clean, formatted) and install the crystalbuntu or I need the hard drive with the original os installed?
3) If I erase the atv hard drive and install crystalbuntu, can I come back on factory reset (maybe using iTunes)?

Thank you all

You can use a clean hard drive. There are a couple of ways to restore the original os but not with itunes. Backing up your own image seems pretty complicated,here is the link for instructions.

What I did was used a PATA to USB adapter and made a disk image using DiskUtility.

A fresh harddrive will work fine.

You will need to restore the disk image using DiskUtility, or check out calev's link. I think Crystalbuntu 2 (which is coming out soon) will have a restoration tool of some kind for the original OS.