If you go to mousesavers they have all of the historical discount info. Your info is basically correct with occasional +/- 5% on the discounts. Resorts offered depend on bookings (they figure out where they're under-booked and release promotions for a certain amount of rooms). Since French Quarter is the smallest of the moderates, sometimes they aren't part of the promotion or they are but run out of promotion rooms quickly (you'll also see that sometimes the offer will be for non-standard room types). I'm pretty sure that if you book ahead, they still technically cancel your res and book a new one, though it's transparent to you (and you don't lose any ADRs or anything so don't worry about that). There isn't a lot of advantage to booking ahead other than the peace-of-mind of having a room (you can make your ADRs a few days earlier, though). If enough people took this strategy, they wouldn't need to give any promotion offers at all. Fortunately, this is Disney and there are a huge number of rooms, so that doesn't happen.
I'm waiting for this promotion, too.