Pretty much every theater showing silent films had an instrument, usually a piano, playing music during each film. Usually the player would just improvise music based on what appeared on the screen, sometimes a film maker would write music for the player to play. As one studio exec noted, there never was a truly "silent" film.
Because doing the latter meant more control over (and money from) his films, Chaplin often wrote musical scores for the films he directed, produced, starred in, and wrote the screenplay for.
silent films.
A film with spoken dialogue as opposed to a silent film where the dialogue is on a card to be read.
Early movies, known as silent films, did not have sound, they consisted only of moving pictures. When movies began to be made with sound, the art of the motion picture entered the sound era.
Yes
Since silent films had no sound, the cards were used for the dialogue. If you have some original cards now, you might consider auctioning them. A collector might be interested, especially if the film they came from can be verified.