> You will experience the same acceleration at terminal velocity that you do on the ground: none.

That's correct and all but the lizard part of my brain would be _far_ more concerned with the sudden change in direction/speed and not super concerned with "at least we're not continuing to fall faster!"

(assuming I wasn't standing by the bathrooms and thus thrown into the ceiling; then who knows what i'd be thinking)

at terminal velocity would you feel that things have "stabilized" and then not notice anything until it stops, when I imagine you would feel crushed into your chair?

Yup. A plane should feel "normal" even at terminal velocity, as the acceleration the majority of the time would be zero, with three exceptions:

1. The start of the drop. This will feel briefly like freefall.

2. The end of the drop. You recognized the gravity (pun intended) of this.

3. Turbulence. The plane will be experiencing terminal velocity wind. I assume this will shake stuff up a bit more than usual inside the cabin.