1. "A golden age is a period in a field of endeavor when great tasks were accomplished. The term originated from early Greek and Roman poets, who used it to refer to a time when mankind lived in a better time and was pure (see Golden Age)." - Wikipedia
This definition alone makes the films of this period part of a Golden Age. The difference I think you can debate here is that in Comic books or theater, Golden Age and Silver Age are more clearly delineated. The medium of film was itself so new that this time period was clearly both a golden age of comedy and slapstick, yet that doesn't preclude other eras to come as also being considered a Golden Age. You would almost have to separate out films by type (esp. silent vs talkies) to accurately define Golden Ages. 2. I agree that the gags were entirely visual. Although, yes, many theaters had musical accompaniment, not all did, and in those theaters that did, not all musicians were of the same caliber. This meant that although music may have been meant to be paired with the gags, there was no guarantee that it would be (or would be paired well) so the gag had to stand on it's own legs. You couldn't count on the cinema cards helping either, as people couldn't all read and in many immigrant populations at the time, even if some of the crowd was reading the cards aloud, everyone in the room may not have understood English enough to "get" the joke. So visual was the only standard that everyone viewing the film could be sure to experience. As to this comedy disappearing, absolutely not. It has morphed some in the sound era, yet there are still films and TV shows every day that heavily rely on visual comedy and slapstick. I think this is one reason films can be marketed to many different age groups. Even the younger viewers can get the slapstick, while the adults appreciate the written bits as well. 3. I think compilations in a way help and in another way harm people's opinions of slapstick (or any film style). In a compilation you may be exposed to artists you were unaware of and that is good, but at the same time the clips chose to be curated into a film are not all the options out there. Sometimes the choices or the sameness of the choices can convince a viewer that he/she has seen all there is to see about a type of film when there is really much more to be learned. That said, I enjoy the compilation films as a jumping off point to encourage me to learn more about what is out there to experience.