Yes, as long as you check in by the last day of a FD promo you can have the discount applied to your entire stay, up to 14 nights. Yes, just wait to call and book your FD package when the offer opens. I would highly suggest going ahead and making your Advance Dining Reservations, many of the character meals and popular restaurants will already have limited availability or even possibly no availability. You don't have to have a resort reservation to make ADRs, so I would do a search now and see what is available on the WDW dining site. ADRs open 180 days before check in, so your ADR window has been open since March.