(1) No, the boat didn't come with a masthead light. (2)No, the class rules don't require a masthead light. (3)I think that navigation rules may require a light at night, but only, as I recall, on boats bigger than an E27. Lights are required at night when at anchor. (4) The main advantage of a masthead light is so that you can see the masthead fly for steering downwind at night. They are cheap and easy to install and don't add much weight or windage.