Parktool has a section on
headsets that should give you an idea of what parts make up a headset. Hopefully, with some figurin' on your part you'll understand how it all works.
Paint on the steerer tube is not an issue. The surface of the steerer should NEVER touch the head tube. Thats what the headset does. It keeps the forks firmly attached and freely rotating on one axis. It is the only structural contact between your forks and your frame.