Doesn't hurt the performance that bad unless you get a badly machined piece.
Doesn't do anything.
The ANS regulator body was designed to compensate for a flaw in the manufacturing of automag valve backs in the early 90's. The air hole in the back did not line up with the air hole in the front. The result was that the valve could starve itself at high rates of fire. ANS came up with a solution here with the ANS back. The ANS back allowed a free flow of air no matter what the orientation with respect to the front of the valve. It worked for older valves.
However, this mod is no longer needed on Automags. Airgun Designs fixed thier flaw back in the early 90's when it became apparent. All mag valves have holes that line up. Therefore, this mod does nothing anymore and is just marketing hype when considered for newer valves. Another deterent from this product was the lack of consistency in its manufacturing. I have yet to see absolute consistency in its usablity. It is hit and miss as to whether it will even work on your particular mag.