1. I can't answer for the 777, but on the 767 the brakes are applied automatically during the retraction sequence. But that should not produce puffs of smoke.
2. The pax display systems I know of take their position and flight data info from the FMS and other flight deck sources -e.g. air data computer for speed & altitude. As all the data required is already present, there's little point in adding an independent source just for cabin display.