Wonderful footage, not seen that before. This type of motor is known as a Rotary Engine, where the crankshaft is fixed and the cylinder block rotates around it. Common in WW1 fighter planes.
Went to a lecture recently [BC = Before Covid] given by an expert on Richthofen. It’s pretty much certain that the fatal bullet was fired by either a machine-gunner or rifleman on the ground. Richthofen broke one of his own golden rules of air-fighting that day - never follow your target down low enough to be hit by small arms fire from the ground. And he paid the price. Interesting bit of pyschology there: why did he do it - why was he so careless? Had he become over-confident or was he suffering from Battle Fatigue?
Probably sexual gratification, trying to make it last.
As a kid I used play the Avalon Hill war games. Reading the historical background sheet in "Richthofen's War", it quoted the baron's war-time autobiography as him saying he "... felt a sudden release ..." after shooting down a plane, along with an editorial comment that apparently the Kaiser's censors hadn't read Freud.