2) The PVC box does not have any clamps inside the box to secure the wire.
Used a white plastic staple to the stud that the box is secured to. The wire inside the box if pulled on can move up and down. Not sure if using a metal staple would be better so the wire does not move. The plastic staple is about 5" or so from the box. Read that when using pvc boxes there is no clamp and the staple holds the wire. The wire seems loose after using the staple. Is this ok?