No one knows yet, they haven't even announced if they're offering free dining to the general public this year. For the past two years, it's been announced in April and was available during August and September, I believe.
Can't really guess as to which resorts will offer it. That decision will be made by Disney based on how booked up the resorts are for the fall.
As stated, it has not been officially announced yet.
There's another thread looking at previous dates as well as the current bounce back dates. Generally UK has the longest window, bounce back the next longest window and the general public has the shortest window.
Yes, while the UK was able to book for stays starting August 10, they were restricted to moderates and above, excluding AKL. The bounceback could be booked at any resort, but the bookings were for stays starting August 30.