1. that is the buzzer sounded when the bus has reached 60kph. it
used to record the number of times a driver exceeded the speed but
now with speed limiters installed & set at 60kph, they dun use
the recording function anymore. but if the bus reaches the maximum
of 60kph, the buzzer will still sound. it is up to the driver if he
wants to slow down. 
2. not sure, but it may be done progressively. the message is not
tat easy to change i suppose. but time change is possible with some
buttons on the right side of the LED.