Sorry I've been gone for so long. I haven't played this game in a few months, but I'll try to answer your questions as best as I can.
It depends on how they're scoring in the paint. Is it from the post-players shooting it too often in the post? Or is it from the AI driving to the basket too often? If it's the post players getting too many shots, just lower the post shots tendency by a few clicks (try decreasing by 2, play a game or two, and adjust from there). If it's from the AI driving too often, do the same thing as above except to the "Attack the Basket" tendency.
I have absolutely no idea what to do for HUM vs. HUM sliders, unfortunately.
If too many open shots are going in, decrease the shooting sliders for whatever ranges need adjusting. Start off by decreasing the necessary sliders by 2, test a game or two, and go from there. For contested shots not going in, decrease the Jump Shot Defense Strength (Release) by 10 (to account for the decreased shooting sliders), and adjust from there as needed.
Whoa, in my opinion the default speed/quickness of the game makes players move FAR too quickly, so if the default is sluggish to you, you will definitely not want to decrease the speed/quickness sliders.