To anchor game objects, use the old UIAnchor.
Skewing may not be that noticeable when going from 16:9 to 16:10, but when you go from 16:9 to 4:3 -- very much so. All your circles will become visibly squished. It's always very noticeable when games do that.
Skewing your entire UI will break your scroll views because NGUI was designed to work with a uniform scale.