2021 Interstate 24 Lounge owner here as well, just picked up the coach last week.
I work on my cars and have a background of electronics as well as construction, but i took the walkthrough at the dealer anyways...
from my experience, the tech who did my walkthrough, he had no idea about the 2021s. i think my unit was one of the first they received.
the 2x bluetooth headset are for the front TV, there's a bluetooth transmitter mounted on the back of the TV. the manuals for the bluetooth, headsets are in the airstream bag.
The rear TV is not connected to any speaker or anything else.
Both TVs are not internet capable. you need to bring your own TV box such as Apple TV, Roku, Amazon Firestick, chromecast...etc, and connect it to the HDMI cables in the cabinet where it house the main control panels. and then connect them to your wifi
The overhead Sony radio powers the rear speakers only
the factory MB radio powers only the front compartment, the sound quality is a joke
You can indeed run the A/C from the 110v adapter, but connect the adapter to a wall plug, not a power strip, it draws so much power and will certainly trip the breaker on the power strip(if there's one).