The last one in the first set and the first two in the second are priceless!
As far as showing pictures, I read before to show a couple through the shoot so that the model(s) can know that they look good. I also read that if you are having problems getting them to get really close to eather to show the results in the camera and that people will tend to move in tighter because they can visualize the difference.
I have found it to be true in every case that people get excited and relax more if they can see how they are doing.
I've had people ask about shots that didn't turn out, whether I showed them or not just because they remembered such-and-such pose.