This is very interesting regarding the right elbow....I have tried to tuck the right elbow more so that I can get it right in front of the hip on the downswing. The problem that I have with this is that many times for me anyway, this leads to the backswing coming too much inside and ultimately in an over the top swing. I find that I have better results when I make sure and focus on extending my arms fully so that I do not come over the top.
With that being said though, every once in a while I will execute perfectly where I can feel my right elbow in the right place and I know in that split second before I hit the ball that it's going to be a good shot. It's a great feeling when it happens. It's almost like time freezes just for a quick second and my right elbow is in the "slot".
As for the left wrist.....that's something that I worked on quite a bit during the winter. I was fighting a slice especially with my driver during the early part of last winter. I found that making sure that my left wrist is not cupped at the top makes a huge difference. I guess in doing this I was laying off, although I'm not sure how much. It did fix my slice though. Once in a while this will still happen and I'll realize that my left wrist is cupped at the top which almost always results in a slice/push to the right. I've noticed that when this happens my tempo is usually getting a bit too quick and slowing down just a bit helps a lot.
I'm no expert so I do not know if this is "right" by the experts or whatever, but it's something that I have gone through and so far (knock on wood), have been able to fix on my own....