I read some of this but not all of it. I would say you are right on some of it and wrong in other parts. Discus do great at 82 degrees. They do not need to be warmer. Bare bottom absolutely does not make them skitish. If you replacement water is correct you can feed before, after, or during the water change. Like I said I did not read this in details. Just pointing out some things that jumped off the page at me.
-john