Coverage depends on ground receiver reception and is not a complete picture of traffic.
The hex code is the aircraft's ICAO 24-bit address, broadcast by its ADS-B transponder. It is the key used to match live position reports to this registration.
The en route cruise encounter with forecast moderate turbulence.
The failure of the flight crew and the tug driver to verify that the aircraft was properly configured for pushback. Factors in the accident were the left wing walker's failure to notify the tug driver of his observations that the jet bridge was still in contact with the aircraft, and, self induced pressure on the part of the captain created by a chain of circumstances surrounding the numerous delays.