I have lots of smart friends, but one in particular is leaps and bounds smarter than all of us. I've spent years observing why that is. Your first point resonates with my observation.
My friend seems to operate with a strong mental scaffolding that allows him to quickly absorb new information -- you can almost see his brain saying "this goes here, that goes there" as you speak to him. This scaffolding also plainly exposes holes in knowledge, which makes him an incredible conversation partner when you're talking about a technical topic -- "you mentioned A, B, and D. Seems like there should also be a C. What happened to that?"
I've known this guy for a long time, and you can imagine that his scaffolding only grows stronger over time, so that it's very rare to discuss a topic with him where he's completely adrift. It helps that he doesn't have the personality of a know-it-all; even if he is a master of a topic, he has an uncanny ability to uncover the thing you know that he doesn't, which makes conversation with him enjoyable rather than intimidating.
Two final points.
One, his memory is not notably better than anyone else's. He forgets conversations and situations as much as anyone else, but he definitely remembers when he's filled a hole in his scaffolding.
Two, his mental scaffolding is very conventional. By that, I mean he rarely has a weird way of thinking about things that makes sense to him but to nobody else. So when he asks a question, it's almost always the same deep question that other experts in a field have been working on, rather than a strange take. While this seems like a liability, it means that his conversations with experts tend to get to the important parts very quickly, rather than wasting half an hour establishing a common lexicon. Maybe I'm confusing cause and effect, and the conventionality of his scaffolding is a consequence of the vast amount of knowledge he's learned and needed to reconcile, rather than the reverse.
My friend seems to operate with a strong mental scaffolding that allows him to quickly absorb new information -- you can almost see his brain saying "this goes here, that goes there" as you speak to him. This scaffolding also plainly exposes holes in knowledge, which makes him an incredible conversation partner when you're talking about a technical topic -- "you mentioned A, B, and D. Seems like there should also be a C. What happened to that?"
I've known this guy for a long time, and you can imagine that his scaffolding only grows stronger over time, so that it's very rare to discuss a topic with him where he's completely adrift. It helps that he doesn't have the personality of a know-it-all; even if he is a master of a topic, he has an uncanny ability to uncover the thing you know that he doesn't, which makes conversation with him enjoyable rather than intimidating.
Two final points.
One, his memory is not notably better than anyone else's. He forgets conversations and situations as much as anyone else, but he definitely remembers when he's filled a hole in his scaffolding.
Two, his mental scaffolding is very conventional. By that, I mean he rarely has a weird way of thinking about things that makes sense to him but to nobody else. So when he asks a question, it's almost always the same deep question that other experts in a field have been working on, rather than a strange take. While this seems like a liability, it means that his conversations with experts tend to get to the important parts very quickly, rather than wasting half an hour establishing a common lexicon. Maybe I'm confusing cause and effect, and the conventionality of his scaffolding is a consequence of the vast amount of knowledge he's learned and needed to reconcile, rather than the reverse.