I was going to check behind the dash, but its been quite cold here in KC, MO, so I'm waiting for warmer weather to take a look while I hard-wire my dashcam.
Yes, I have LDW and Adaptive Cruise Control. The vehicle has not been in a collision to my knowledge, nothing on the history report or reported by Carmax. It did have non-title hail damage reported by the auction firm on the history, I can only find two tiny dings with the right light shining on them.
I don't think the cluster has been removed, but who knows. Also, it's not a series of 10 beeps, it just beeps constantly until it goes back under 80. And like you said, it doesn't happen in reverse.