Jetstream Rider, that link you provided only discusses one idea on how the downwash is created. The "4/5 of lift [that] comes from the top surface" is also generated by deflecting air molecules against gravity, its just that its not doing it through a collision with the lower surface of the wing.
Interestingly, areas of lower pressure don't pull. Instead, areas of higher pressure push. Granted, these are definitions we have made, but intuitively, what is attaching the area of low pressure to the surface it is supposedly pulling on? With this in mind, I'd find it interesting to see how Kermode has decided that the top surface is producing more lift than the bottom surface.
The spinning cylinder redirects airflow. Creates downwash in the production of lift. This is consistent with momentum theory (and inconsistent with "skipping stone" theory). Not sure why you brought this up.