M.O.
My big question, which you answered partially, is whether he has conversations. Beyond question-answer sessions, does he converse back and forth?
My own son was a little slow to talk, but on his third birthday (literally, on his birthday) he began to converse. I remember this huge conversation about whether various animals, toys, and cars were "pretend" or "real."
If he does converse, the question thing honestly sounds like a minor quirk and something that will work itself out in time.
If not, there might be a language-processing or social-processing issue going on, but either way, he sounds super-smart. It's very common for highly intelligent kids to be "twice exceptional." And with greater intelligence comes greater and more creative coping capacity, though it may not always be a smooth or predictable road.