With regards to the elbow I would say that you definitely need some space from the body, the elbow should also be in front to allow the forearm to hinge outwards and push forwards in the shot. Yes that could for sure explain the two things you mentioned above, you should be right behind the ball with your body when playing backhands and the ball should be contacted quite close to the body and not reaching too far in front to keep the control.
Answer for backhand-technical-question-2
