Answer to Question 1
A five-note pentatonic scale D E F A B (You can hear the same kind of scale if you play the black keys on any keyboard instrumentF G A C D.)
Answer to Question 2
Ban are metrical strong beats, equivalent to a Western measure.
Often solos for pipa--either as short, free-standing pieces or as part of a suite (grouped with other solos into a compilation)--were exactly sixty-eight ban in length.
--Study the accompanying Active Listening guide as you listen to Da Lang Tao Sha (Great Waves Washing the Sand.)