Answers: We talked about this hobby; kids are irrelevant to our friendship unless they a) join us, or b) cause scheduling conflicts; we're collecting things related to this hobby; and I honestly don't care about his volunteer interests. Our friendship begins and ends with our mutual hobby.
To be clear, I'm not joking. That's essentially what many male friendships are like. If I find out they're a Nazi or something, the friendship is over, but most other things are irrelevant.
Kind of? Typically knowing what someone does for a living gives you a pretty good insight into their background and what type of person they are. It's not a universal truth, but mechanics are usually very different from doctors.