Yeah, it seems the Superman animation (and other Columbia serial animation) was done at the Swift-Chaplin animation house. (Yes, Charlie Chaplin was the finnacial partner.) They did animated titles (and provided stock space shots from the CAPTAIN VIDEO serial) to one season of ABC's SPACE PATROL, and a lot of 50's commercial animation.)

I agree with Don that while Kirk Alyn was fine for the serial, he lacked the depth (and later, paternal warmth) that Reeves brought the role.
From what I understand, Robert Maxwell wanted an all-new cast for the TV series, to make it clear that this was a fresh start. Maxwell wanted to make tougher-minded stories for the entire family, and not just for kids, as he had been trying to do on the radio show in its final years.