One problem I've noticed is that no matter how good of an example I set (arriving early, being prepared, being honest and fair, etc.), many of my students do not adopt these traits. Of course, that's no reason to stop doing them, but I wonder to what extent it's my responsibility to or if it's even possible for me to teach non-idustry-specific characteristics such as politeness (not talking on phone during class or leaving repeatedly, etc.) and professionalism (punctuality, meeting deadlines, conflict resolution, etc.). My grading structure and course requirements reinforce these things, but many students just don't care.

Regarding the lesson about being a friend vs. being a pal, I agree that being too chummy can be dangerous and blurs the professionalism line, not to mention the impartiality one needs in a classroom environment. But I believe developing closer friendships with ex-students is acceptable. Once you no longer have sway over their grades or them meeting the requirements of your course, there's really nothing to prevent deeper friendships from forming, especially if said friendships lead to professional projects together.