Nice report. We were on the Magic not too long before you. There are elements of real gingerbread on the house, and it smelled good in mid-November.

and yes, there are normally chairs/sofas in that space when the gingerbread house is not up.
Atrium is definitely super crowded for some of the performances they do in there. (we also had a few rude people on our cruise-- I watched one lady berate a little girl for trying to get a view of the Christmas tree lighting-- she could have scooted over 6 inches or let that little girl get in front of her and still see. And yes, maybe that little girl's parents could have gotten there earlier, too, but the lady who wouldn't scoot over was not nice.)
That is weird if your adult friends/tablemates let the servers cut their food. I can see them doing that for kids, or when they remove lobster meat from the tail or cut shrimp tails off, but our servers certainly let us cut our own regular food! We had good servers who were the right amount of attentive--not too much, not too little.
Theater-- I agree. We didn't notice too many people try to come late, but it happens. If you are not in need of it, you wouldn't know about the entrance through Keys that goes to the front of the stage for accessible seating. They only let the people who need it go through that way, from what we observed on a previous cruise.
I don't recall it being a zoo for embarkation at Miami-- sort of crowded. Embarkation at San Juan for the Nov. 15 cruise was a hot mess, though.
And isn't Gus cool? We did one of his animation classes and really enjoyed it.