When astronauts move around inside the ISS, pushing off walls to stop and go, how does it not affect the inertia of the ISS, and send it rotating undesirably or off course, little by little. I expect the effects would accumulate quickly, unless the astronauts remained perfectly still all the time. Even though the astronauts are small, relative to the size of the ISS, I would expect their behavior to affect the motion of the ISS, the way a construction worker can affect large objects that are hanging from a crane. Also, during a spacewalk, if an astronaut interacts with a ladder, or something extended from the ISS, I would expect that effect to be magnified, since leverage is involved.
It doesn't make sense to me that the ISS seems (based on video feed I've seen) to have one side constantly facing the earth, instead of rotating.