I'm pretty sure you still need mechanical filtration if you're using LR
as a filter. The rock only provides biological filtration. When i think of mechanical i think of carbon and a skimmer which you need with rock(skimmer absolutely, carbon is optional).
A filter without any media is just a powerhead and yes you would need some sort of device to create waterflow. The biowheel attached to the filter is just there for extra biological filtration which the rock is already doing. I think it would be necessary at first to develop the bacteria, but once its established, you could take the biowheel off and the tank would still thrive.
In fact the wheel can actually lead to a build up of nitrates which is why most people who have alot of rock in their tanks get rid of bioballs/biowheels/etc.