Think of the wings of a bat, which dragon wings are based on, as an arm with long fingers and skin between the fingers, like this- link and this- link.



1- In a bat-like wing these are actually long fingers and should all be coming out of the hand instead of the side of the arm in various places.

2- This is where the hand should be, but since in a bat-like wing most of the fingers are very long with flaps of skin between them all you should actually see here is just the thumb, rather than an entire hand with its own fingers.

3- I'm a little confused as to why this has a couple of joints here. It should simply be a normal shoulder with the arm extending to an elbow, then a forearm, and ending at the hand and fingers.