It says a lot about the culture of the 60s and/or Pohl himself, that the first conceivable use for “instant ordering” would be for drugs.

… Pocket bar? Googling it gets me nowhere. Surely he didn’t mean a bar of alcoholic drinks? Maybe a pocket pry bar?

Feynman, mainly because he was an amazing professor and knows how to talk to people.

Einstein and Newton disliked people, so they would be terrible conversationslists outside their areas of expertise. I think that was true of Leonardo as well. Edison is also out because he was a dick.