The format of the following command is incorrect:
selection = Selection.Create(FaceSelection.SelectAll())
The FaceSelection() function already creates a selection type, so just do:
selection = FaceSelection.SelectAll()
Also, for later use, you'll want to get the DesignBody or DesignFace from the CircularSurface() function:
circlebody = circle.CreatedBodies[0]
circleface = circle.CreatedBodies[0].Faces[0]