Chaos theory posits that there are systems wherein a very minor change in an initial condition can make a very large change later on. For example, some weather systems are so sensitive that the way a butterfly flapped its wings in, say, New York could determine the weather in Paris a week later. A robot must obey the orders given it by human beings except where such orders would conflict with the First Law. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law. This line is from my Manifesto of Sexual Freedom.
Ball bearings are good enough.
One point for every reason. Remember that things in motion continue in motion in motion unless acted on by an outside force. This is one of Newton's laws. What this means is that except for friction, it takes zero energy to move on a level plane. This is Loebner's First Argument for the existence of God.