Nitpicking but it's annoying - Why does this post insist on using the singular 'they/their' (in reference to Satoshi) when the normal 'he/his' would suffice and read much more clearly?
I doubt anyone would be upset at people using he/him when referring to Satoshi, but also along those same lines, it seems strange to be upset at they/them usage for an unknown entity.
In terms of individual vs group, it seems unlikely that a group would have the discipline to not do anything with billions of dollars or expose the individual with control of the same.
As long as you don't know it's a pseudonym, yes. I don't know when that became generally accepted.