Why weight matters with the size of the board you get, and not height?
neither of them matter that much, the type of riding you do dictates board size more than anything
Why a free-style board is a shorter board with more flex? how a shorter board gives more control and maneuverability.
they are shorter so they are easier to throw around and manipulate, a board that is torsionally softer is easier to turn at slower speeds, therefore you can control and manouver it better
Why a free-ride is a longer board, stiffer, and more stable?
because thats what you need for that type of riding, sort of self explanantory
I'm having a bit of trouble understanding how some people say a softer free-style board lets you turn more easily, and then reading that a longer free-ride board is more stable and allows quicker edge to edge transition.
how quick a board is edge to edge has to do with its sidecut and waist width, not how long it is
Also stance width. wider stance, more stable; more narrow stance, easier edge to edge.
this statement is too general, its not hard to turn with a wide stance, just find what is comfy and works best for you