the skaven would also have to test for confusion. It does not matter when the shooting takes place, it is worked out when the attackers have reached their final position (says so in the rules), so the skaven have to test, too.
About the example: dragon + unit can shoot all their shots at the attacking unit; if the attacking unit creates frontage with 2 stands, then 2 other stands can shoot back (depends on what stands are in contact, as the dragon has more attacks). Mind that corner contact does not count as contact in this case!
bg,