Electrons crazy behaviour

Okay... Im no established scientist and I don't get some big words but in as simple terms as you can manage in a full explanation could somebody please resolve this confusing problem:
My physics teacher tells me that metals conduct better than other substances by having 'free electrons', meaning that electrons are free to bounce around from one end of the substance to the other quicker than the other particles because they are smaller. So in this instance they make contact, hitting each other and bouncing off each other. However, the same teacher tells me that in the structure of an atom, on energy levels, the electrons repel each other and stay away from each other as possible. I realised this issue straight away and asked him what the deal was, but he has no idea. This makes me skeptical on what he has been telling me. My point here being that in different circumstances, why do the electrons behave so differently?

I've taught chemistry and physics for almost 40 years. Let me see if I can resolve some of these issues. The first has to do with "metallic bonding", in which metals are described as having metallic ions surrounded by a see of mobile electrons. This is the "electron sea" model. The catch is that the electrons are not really free, they are still "part' of a metal atom, but they are easily moved from one atom to another so that metals easily conduct electricity. In fact it is the repulsion of electrons that allows for the conduction. If a force is acting on one electron and moves it to the next atom, then the repulsion would force an electron in the adjacent atom to move to the next atom, and so forth. The electrons themselves move very little, but these small motions result in the flow of charge, and that's what electricity actually is.

This statement is not particularly accurate: "metals conduct better than other substances by having 'free electrons', meaning that electrons are free to bounce around from one end of the substance to the other quicker than the other particles because they are smaller." The electrons are pushed from one atom to the next, but do not move from one end to the other. The electrical charge moves through the conductor at nearly the speed of light, but not electrons themselves.