Advise required - 2 backups, one My Book Live

So my brother and I have purchased a 2TB My Book Live to back up our Macbooks as we both have design related jobs, if our machines break, we lose everything.  As well as liking to automatically back up, I would like a film folder to act as a library for us both to share, either stream to our xbox’s or download of the HD.

First of all, the first thing I need to do is completely clone my Macbook hard drive off my mac to the MBL, format my macbook to fix a GUID partition error when I installed the new internal hard drive, upgrade my iOS to Lion and then put everything back on.  With that in mind, I’m going to use the program Carbon Copy Cloner, which I imagine will be relatively easy to do.  My question at this point is, what do I need to format the MBL to so I do not damage any permissions/files in the process of this, and will I need to re-format the MBL to accept our automatic back-ups from our machines but still be able to access it from a PC/windows OS machine (xbox)?

To sum up:

  1. Do I need to format the MBL for my intial hard drive clone?

  2. What format does my MBL have to be to accept the automatic back ups from our macbooks, but still be able to access from n xbox and a PC if needed.

  3. What is the best way to automatically back up 2 machines to 1 MBL?

Thanks to everyone that can help!

  1. The internal format of the MBL HDD is EXT3, but if Carbon Copy Cloner support backups to a network hard drive, it should work regardless of the HDD format.

  2. You cannot change the format on the MBL, but any device that can access a network storage should be able to do it. 

  3. If you would like to backup your files and applications, is better for you to just use the time machine app that came with your Mac to make a backup of both of them.