The phrase "above the salt " and "below the salt " indicates social status, or at least it did during English banquets of the Middle Ages. If you were invited to eat at the head table with the lord of the manor, you were "above the salt." Everyone else was seated "below the salt." I've always assumed that the salt was placed somewhere between the head table and the other tables.

Regarding salt cellers- When I was growing up, these were used at "dining room" meals. My mother's were very small glass or crystal dishes with tiny glass spoons. They were always placed above and slightly to the right of a person's plate. I also remember that dipping a radish or green onion in the salt celler was not considered good table manners.