I'm not sure if IMDB is a reputable source, but according to it, Henri Delannoy, who played the Captain of the rocket, lived until 1976.

Sorry, slight spelling error in title, it's Georges Méliès

To address part 2 of your question:

the film ends with a space capsule landing in the ocean. Was it pure chance that the film's ending matches the ending of many mid-century space missions, or by the early 20th century was it known that a rocket space mission would end in the ocean?

The film drew inspiration from Jules Verne's similarly titled novel "From The Earth To The Moon" and its sequel "Around The Moon" which described a similarly bullet-shaped projectile spacecraft.

In the second book, the spacecraft splashes down into the Pacific ocean and the three men aboard survive and are rescued, but not before an Apollo 13-style close call which sees them suffer from toxic gases on board the spacecraft, fail to land on the moon and orbit it instead, and require a timed rocket burst to correct for being off-course, and then almost crash and die upon re-entry to Earth.

The novels pre-dated the actual moon launches by around 100 years: they were written in the mid 19th century. They also successfully "predicted" a few other things by chance, such as the launch site being located in Florida.

Obviously Melies' film was not a straight adaptation of the story. It also drew some fantasy elements from H.G.Wells' "The First Men in the Moon" in which men land on the moon and meet strange alien creatures.

But my point is that various scientific accuracies in the film pre-date the film by about 50 years, and go back at least to Jules Verne, whose story would have well and truly been part of the public consciousness at the time.