So how about telling us what the attempt to do these things actually does.
When shooting a shot, what do you think holding the cue tightly actually accomplishes?
Slows down the cue a bit due to muscle tension, may cause a slight lifting of the tip before contact, provides a different "feel" due to your grip dampening the vibrations that occur after contact. The muscle tension will affect different strokes different ways, and can be almost counted upon to affect where your tip actually hits the ball vs. where you intended.
What does the attempt at holding the cue tip on to the cue ball for an extra nanosecond do?
If you're trying to hold the tip on the ball, to me that implies you're trying to sneak up to it and "push" rather than "hit". What this really means is hitting it a lot softer, because you delay the acceleration of the cue until it's close to the ball and doesn't have much room to gather speed.
What does the attempt to accelerate the cue stick through the cue ball do?
It generally ensures that you accelerate the whole way TO the ball, meaning you hit with more speed. Also, thinking about acceleration for me leads to a subconscious idea of smoothness (rather than jerkiness), which is conducive to a more rapid muscle contraction, which also means you hit with more speed. So you're using a mental trick to just plain hit it harder.
What technique in shooting a shot can reduce the amount of squirt? (using the same amount of side spin)
Only hitting it softer (or using a different shaft with less tip end mass). Of course, as I've said, many of the mental tricks people use probably do result in hitting is softer, and thus decreasing squirt.
Thanks,
JoeyA