#1
7 9 10 9 7, using index for 7, ring for 9, pinky 10.

Is it better to play the last 2 notes by lifting up the pinky then the ring finger to let the 9 and 7 sound? Or is it better to fret it as if you were fretting 10 9 7 (lift up all the fingers, fret ring then fret index)
#3
Play 7 - 9 - 10 and keep all the fingers down, then lift pinky, lift ring. You always want to try to leave your fingers down whenever possible, it provides stability for your hand.