WOW. What a great post PGStaff. Thanks for the detail and keeping it simple enough for high school hitters to understand. To the comments and questions.
2. Watching the opposing pitcher pitch to other hitters. Though I did not include this in the question, speaking with the earlier hitters about anything that confused you or you might have missed during the observation phase is, of course, a good thing to do.
3. On deck preparation to hit. Go through the at bat with each pitch. Swing the bat at each pitch making the adjustment as you see the release and/or pick up the flight of the ball. Is that what you mean by timing or something less or more? Form your plan [now knowing the exact situation you are facing] as you stride up to the plate.
4. Upon Entering the Batters box. Check the fielders. Have they made any adjustment that might interfere with your plan. You are right in that much more could be said here. One question, if I may? For high school hitters, once all that preparation is undertaken and they are 'set', should they try to clear their mind to a "see the ball, hit the ball" mentality or what? In somewhat different words, should the hitter trust that his body will do what his mind has planned or should he be, like Crash Davis, saying to himself, "give me the cheese, meat" or such to remind himself of the plan or the pitch? Or does it depend on the player?
5 & 6. i have no comment other than IMHO I think your analysis is absolutely right on and have never heard it said or written better anywhere. Excellent analysis.
7. Should the hitters approach change in subsequent at bats? Would your answer be different if he was successful in earlier at bats than if he was not? I completely agree with your point on what is the hitter's job in this [later] at bat and if it is different from the first at bat he must plan accordingly. Especially if he has had success against the pitcher in the earlier at bats. But if he has not had success, at some point should he consider going to a 2 strike mental approach right of the bat [no pun intended], look for a bunt opportunity, etc. or is the possible loss of confidence by going into that mind set potentially more damaging than the inability to find success against this pitcher with his previous plan(s) of attack?
Thanks for the excellent input and thanks for the kudos on topic selection. I think this is something that high school students don't get a lot of and need to. I hope that others submit their ideas.