Also the reason the circle is not following what you would think is the normal of the path is because you are trying to use a closed circular path. I am not sure why it does what it does but if you cut that path in half and then extrude the closed circular profile along each half circular path the normals will be as expected.

In other words if you extrude along an OPEN path the profile will remain normal to the path tangent.

I cannot explain why it becomes skewed when extruding along a CLOSED periodic path. It is just one of those things you have to deal with.