And I'm really talking about the school of thought that one skill should not lag too much behind the others.
1) Doesn't that kind of answer your own question?
In my opinion, it's all up to the user. I don't value Shot Blocking so much as I do Inside Defense and Rebounding -- as I run a mainly Outside-shooting oriented offense. Thus, I don't value Inside Scoring all that much, either. They're nice if they come along, but I'm more concerned with the other two. Other coaches will have their own priorities, depending on how they want their team set up.
2) Outside Shooting improves Jump Range primarily, with (at least) Jump Shot as a secondary. Jump Shot trains itself as a primary... I'm not entirely sure what it's secondary is.