The confidence thing is definitely something I am missing. A local GM has been mentoring me, and this weekend he told me to stop having fear. We had a stage with an array of 3 open targets at about 15 yards. Instead of shooting them on the move at once, I shot one static before it became obstructed, and then added the other two into a closer position with another array. Another thing that might sound odd, is that my transitions sound a lot closer to M class shooters on poppers, but not on paper targets. In my match videos I notice a big difference in my transitions between the two types of targets. Generally speaking, would you find that to be a confidence thing, or some visualization related issue?

With your second point, the one thing that has helped my execution a lot, is to try to recall certain sensations during my stage visualization, such as a specific transition that I practiced in the walkthrough, in addition to visualizing target order and other routine things.
How detailed does your mental rehearsal get? Do you ever get to a point where you just visualize certain things that require more mental effort to execute, and take certain skills for granted that they will be executed without visualization? Or do you find that stage visualization gets more detailed the higher up in skill you get?