Im looking to get a 750gb HDD. First. Will time capsule back up everything? So if i have 65 gigs worth of data on my computer it will back up all 65 gigs. Meaning the External would be 750-65 = 685? Or is it some type of compressed format? Second Can i use the external to store all my music files on. Like move the itunes folder over. So that when i connect my ipod to my computer, my external must be connected first.