I think 3. with items happens when there is water that is moving back and forth on the ground and for some reason that applies ridiculous amounts of velocity to the items in it, and I don't think is intentional.
As for 4., I believe a body part with very low skin health can get infected if you don't cover it with bandages. Your character tends to communicate this risk to you I think unless there are more pressing matters at hand, and I've noticed it does get infected eventually if you don't wrap it up or heal the skin fast, even if there is no bleeding wound on it or you cleared out an infection on there before.