My understanding of the backup (after trying to initiate one) is that 1) you can't choose what is restored/only restore part of it, it has to be the entire thing. Timewise: my system was only backed up for 3 months, but it might differ depending on how large/small your instance is.
I'd put in a support ticket to get additional information since a lot of this is dependent upon what was in your contract when you signed up.