1) Great questions are influential as they set the frame for a conversation and provide a measure of power and connection. Questions retrieve information and create new connections between different data points.
2) To ask great questions, one must build rapport by demonstrating interest, matching physiology, stories, and language with the other person. Great questions get at patterns of behavior and how they relate to the questioner's intentions.
3) An example of a great question is "How much of your time do you spend solving problems?" which can reveal what motivates, what someone notices, and how they respond to problems without directly asking about those things.