There isnt an instance that is pronounced that you can "see" it. It is subtle and involves your stepout, your step into the ball, and your recovery. Just work on it.
You need to move in more of an athletic stance. I am not too picky on how low, but given that you occasionally bend your knees well on shots, I would move to a more pronounced athletic stance to strengthen the quads and calves so you can improve your endurance in this area.
For toes, yes, you need to get over the balls of your feet and move more from them. You need much less heel to ground contact. Heel to ground contact slows you down and is a killer when trying to change directions.
Watch Federer:
http://www.youtube.com/watch?v=NVwPRKh1Mdk
Yes. you dont have to keep doing this as you progress. This is an exercise to help increase involvement of your non-dominant arm. Just look at how you finished at the last frame.
You are not terrible in this area, it is just for my taste, I would rather see club players get into the ready position and recover qucker maybe than others.
Players need to setup with their legwork. Plant and then turn INTO the ball. Extension is important because it helps to provide feedback that the players sent their energy through the ball. Many times we dont do this because we nervously try to move back into position too soon - so we cheat ourselves on our shouder rotation for the stroke. First off, if a player is thinking of moving back too soon, they are not concentrating on the ball well. Their eyes may glance away from the ball too soon, etc...without them knowing it.
Finish your stroke, place your front shoulder unders your chin, then move thatback shoulder back into the ball. To help reduce "cheating" back to the recovery position so you can relax through your shot, make sure you chose the right shot to hit to begin with, and be more aware of your shot selection mistakes.
An example of a shot selection mistake can be one where you try to do something with the ball (hitting DTL) to put pressure on your opponent only to find he is putting pressure on you because of the shot you chose. Rotate through the ball, use your shot to (pace, placement, selection) to give yourself a chance to recover to a closer position (hitting crosscourt) on the court.
No excuse, this is footwork. You need to work on it. You need to work just as hard on your footwork as you do your stroke. Your footwork is everything. It is your foundation for balance, execution of the stroke, your timing, and your recovery.
Just keep doing what you are doing. The long L for a onehander is something I watch for. Many club players think they are Federer and so they start turning the wrist to impart topspin. They try to duplicate the WW wiper pattern of the forehand. Sometimes they hit a great shot which gives them a false sense that they mastered this movement. I am more concerned with your racquet face meeting the ball on time and cleanly then I am imparting a bit more topspin. Just extend naturally through the ball, you are doing fine, dont overthink it. You have other things to work on which is why I said I liked what you are doing.
No tentativeness allowed for a onehanded backhand. That would really spell doom.
Could be a lot of things.
1. Starting and finishing above the ball too much.
2. Not tranferring the weight quick enough (hitting more off your back foot or inbetween).
3. Coming up to fast on your swing to impart topspin.
4. Contact point.
You need to turn your shoulders more.
That is good. Just do a little more shoulder turn and be consistent with that and you will be fine in this area. Not a biggy.