Question 1: Why it is not possible to measure the drift speed of electron by timing their travel along a conductor?
It is not possible to measure the drift speed of electron by timing their travel along a conductor. When a potential difference is applied across the ends of a conductor, an electric field is set up at every point of the conductor. The free electron now feels drifted opposite to the direction of the applied field. During the motion of free electrons, atoms of the lattice of the conductor come in their way. The collisions with the atoms of the conductor continuously change the path of the electrons. They move in different unpredictable directions. Therefore, their path of motion is quite inconsistent. In order to reach the other end of the conductor, different electrons take different paths inside the conductor depending upon their interaction (collisions) with the atoms. So we can’t say an electron about the speed of electron by timing their motion from one end to the other of the conductor.