I want to ask somebody a specific question, but I'm new here and I don't know the proper protocol. Can I ask a question directly to a specific person? If not in a private forum, does Stack Exchange allow generic questions/answers that may/may not be of interest to anyone else? Questions such as, "Do you have a reference for your answer?", "Is this your profession?", or "How long have you been in this industry?" Those types of questions.
Questions of this nature would be generally off-topic for the main site.
For contacting a specific user you can see if they publish contact information on their profile, or check in the site's chat room (many of us hang out there).