In short: you should conduct yourself like a real curious human adult talking to another real curious human adult.
And you should understand that, at a research university, your professors are primarily here to conduct real and new research into our fields of study. The research university did not hire us (in most cases) to help you understand books or navigate a field of information—they hired us to write those books, to define and expand the field, to discover, correct, or refute the information. That’s what we do whenever we aren’t teaching: it is hard and intense work and, yes, it is what we do during the summer (our busiest time of year).
And that’s why you’re here. You’ve left high school, where your instructors’ expertise was primarily in molding and advising and encouraging young minds (very important work!), with only a secondary mastery of whatever field they taught, material that they accessed from the books that university professors write. You’ve now come to study directly with the experts themselves. Our primary concern is the material itself, not your personal growth.
Luckily, many of the experts care a great deal about teaching effectively—a concern that comes primarily out of love for our fields of study, out of a wish to increase public awareness and understanding of the field. Most of us are also continually working to improve our teaching…
…though our employers’ demands on us for new research are constant and urgent, so we must carefully negotiate for any extra time allotted for non-research work. My writing this right now has taken about half an hour away from my progress on a book that, when finished, will attempt to massively correct the way modern readers understand a particular set of medieval plays. Such losses from research time will delay the completion of that book, which will negatively affect my pay and promotions.
The best online resource I’ve seen in response to questions like this is Sonya Huber’s brilliant Shadow Syllabus. Read it — it’s short and brilliant.