Incorrect (currently). They allow you to delete after you deactivate, but they make you wait 14 days while deactivated in the hope you realize you need facebook.
Well are you sure, that this is not only, what they tell you. Are you sure there is no table in their database called "deleted_unrecoverable_profiles"?
No one can be sure if it is that way, or if the data is really deleted. And knowing their take on user-privacy, I tend to believe, that data is never deleted by Facebook.
Even if they do delete it and never back it up, it seems very unlikely they'd go through what must be a huge library of backups and wipe you from all of them. Such an expectation would be ridiculous, and I'm sure pretty much no company will do that, but the point is your data won't be deleted from all sources regardless.
No. This is marketing spin. Your data is NEVER DELETED. I'll bet you paychecks that FB has archives of all their users data.
One example: a person committed a crime and stored evidence on FB. FB retains user data forever. They might not make it public, but the data is not deleted.