I think the three questions are his main focus. Having a nice conversation and asking questions is just the example method used to determine the answers. It's not revolutionary, but showing that individually they are all necessary but not sufficient conditions was novel to me.
I think AS wrote a blog post. He probably didn't have the experience to back it up.
I don't hold it against him. An ordinary young person being a young person. Nothing special. Nothing to be embarrassed about.
Also I don't think he cared about the hiring much - his specialty was never upper management.
Of course you want smart, curious people who can learn things and do stuff. These "guides" are just various elaborations of (sadly uncommon) common sense. There's no secret here.