1) A screenplay is a technical document that tells a story in pictures through sluglines, action, character names, and dialogue. It provides instructions for what the audience will see on screen.
2) The key elements of a screenplay are the slugline, action, character names, and dialogue. A slugline indicates interior or exterior location and time. Action describes what is happening visually. Character names appear in all caps above dialogue.
3) Dialogue is indented and follows rules of capitalization. It has no quotation marks unless quoting another character. A new slugline is needed for a new scene in a different location or time.