For this discussion, I am going to call the piece of material I am cutting the "workpiece" and the thing I want to end up with the "model."
I have been playing around with the stock value and it does seem to control the thickness of the total cut (rather than the depth of cut). However, the program should know where the edges of the workpiece are because I have given it a cylindrical workpiece of known dimensions. If I set the "stock" value to 2, it generates toolpaths that are outside the workpiece. The toolpaths follow the contours of the model and cut air. It makes no sense at all. If I set the stock value to 0, it makes just one path a final dimension so the depth of cut is huge. I have tried negative values for stock and it won't calculate any toolpaths.

Do you think that 2D countour would produce better toolpaths? If so, how to you tell it that you want rotation of the A axis?