ticklemejoviemo

Good evening. Entirely new to home theater, at most ever had was a soundbar. I recently purchased the following Klipsch: 2x R-625FA + 2x R-41M Bookshelves + R-52C Center + 2x R-120SW Sub and a Denon AVR-X3600h. Setup is in basement with 81" tall drop ceiling. There is 42" between upfiring atmos speakers and standard 2x4ft drop panels. Realize probably not best material for reflection so wondering if should replace some of the tiles in that area with maybe thin plywood or something else more suitable? I CAN set the distance from the speakers to ceiling in Audyssey. 2nd; I'm considering 2 more atmos speakers. considering my couch is backed against the wall and my rear surrounds are on wall with brackets angling them down & in towards listening position, I was thinking the cdt-5650-c II's possibly above couch... However, the literature I have read on that makes no mention of atmos... Is atmos just a marketing term and you can essentially use any speakers as long as plugged into height channel or is there something I'm not aware of? pardon cluelessness, but any help greatly appreciated! Thanks so much!