As PP mentions, current status of CC is unknown until reports come in if hurricane damage. There is a First Aid location on CC; that is probably the only place an adult could lay down for a diaper change.
I haven’t heard of changes to the Dream shows, though they may vary by itinerary. But
prior Navigators can give you a good idea. I’m not sure I understand the question about the D Lounge sometimes there are activities planned there (character meets, Bingo, towel folding, etc.) and those will be listed on the Navigators as well.
“Quiet” cabin may depend on neighbors. Ends of hallways (further forward and aft) will have less traffic than midship near the main elevators. Connecting cabins are in all areas, check some deck maps. I like
https://www.cruisedeckplans.com/ rather thank
DCL’s site.
Enjoy your cruise!