is the key to throwing a good changeup griping it deeper in the palm or pronating early or both and does the grip have to do anything with that

For my changeup (circle change) I move my thumb up a bit higher on the ball to reduce some velocity.

My pitching coach of many moons ago once told me that just about any pitch can be turned into a nice changeup, and he demonstrated a few of these for me. The key is to throw the change with the same arm motion and the same arm speed as you would the fast ball—you have to avoid telegraphing the pitch. As for the grip, there are quite a few you can use—for example, in throwing the palm ball you would grip the ball way back in the palm of your hand, all four fingers on top and the thumb underneath for support: but don’t grip it too tightly, because you don’t want to squeeze the juice out of the ball. For some other pitches you would just use a looser grip. As to the circle change, if you find you’re having difficulty forming the complete circle with the thumb and index finger you can use a backwards “c”, which will work just as well. 8)

Be careful with that as it could result in supination into release. It can also result in the ball squirting out to the side (i.e. affecting control).

With young pitcher, I prefer a grip where thumb and middle finger split the ball in half.

throw the backinside of the baseball. pronation comes naturally. its part of the process of the arm slowing down.

I don’t put it up too high, just a smidge.