Echoing some of above.
1)Toes up, particularly with the left foot(rt. foot looks okay) and perhaps slow down the forward movement speed.
2)Toes up, and quicken arm action.
3)not familiar with that drill
4)Bend/fold the leg into a tighter angle(the legs are opening up too soon largely because they are not folded enough in the first place-IMO) and emphasize the quickness and flexion of the knee (rather than the action of the foot as this swinging action should occur more easily, naturally as a result of what happens before it) much as a hurdler would do with their lead leg. This should shorten and thus quicken the lever.