Big if, don't you think? Rarely works out that way in my experience. And forced learning isn't entertainment, it's a means to an end.
I think the "if" is smaller when you seek out that type of relationship. What I've found out, too late, is that most professors want to be that type if teacher and a good student can bring that out of them. You get what you put in. Wikipedia = a Wikipedia education. Seeking out a deeper interaction with your professor = a deeper education.
Depends on the professor. I have a business degree and some of my professors seemed to almost crave the ability to discuss beyond the topic. There's subjectivity in business too and where there is subjectivity, there can be great discussions to have. I would agree though that those moments are far more abundant in the arts.