The first time my boyfriend saw one of our boys do that, we were laying on the bed watching a movie. The chin was standing all stilty just before the act and my boyfriend went, "Oh, look what he's doing, that's so cute!" His face quickly turned to horror as he buried his face in the pillow and yelled. He would peep up to see if he was actually seeing what he thought, yell (AAAARGHH!!!!) and bury his face in the pillow again. It way so funny. And me, being an animal science student, was totally unfazed.
As for the poo-eating, yeah, it's totally normal. They get extra protein and vit. B from their feces, as it contains some bacteria from the cecum. I know it's pretty important for rabbits to eat their feces, so maybe chinnies as well? I know their digestive systems are kind of similar.