For #2, I don't see how you could ever be completely sure the other was rationalist or Bayesian, short of getting their source code; they could always have one irrational belief hiding somewhere far from all the questions you can think up.

In practice, though, I think I could easily decide within 10 questions whether a given (honest) answerer is in the "aspiring rationalist" cluster and/or the "Bayesian" cluster, and get the vast majority of cases right. People cluster themselves pretty well on many questions.