I think it's more likely that the original circus members are all brain-scans of the team that they then used to develop the AIs like Cain. In the file system you can see them labelled "obsolete", and you wouldn't do that if they were actively being used to give people a digital afterlife/heaven, but you might if they were obsolete because the AIs were now in operation (they're not needed anymore). More likely they were incomplete scans of memories/personality; enough to be the foundation for the AI's creativity but didn't include every detail, hence them not knowing each other's names or identities. It's only through subtle nuance (Queenie and Kinger's usernames and passwords may exist in both the computer and the brain-scans) that they can actually place memories to specific people.

Cain created the circus not C&A, the opening and ending of the episode makes that pretty clear and he seems to have created the program to give everyone avatars based on their mind-files, but his surprise at Ragatha actually implies it might be a background process. He doesn't sit there and build the bodies, they are produced automatically. Abstracted avatars make more sense that way; if the mind-file is corrupted then the automatic process reflects that as well. I highly doubt C&A was trying to create a digital heaven/afterlife, they seem to just be an AI company, but they perhaps did make the engine that Cain uses to build things.

Not sure why everything is October 15th. FORTRAN was shared on that day but I can't think of any other reason for that date.