Major writing number 1

The analytical report describes an assignment in which we have to go out and interview both students and professionals. The purpose would be to compare and contrast how writing professionally differs from the classroom. I could see myself in particular learning many new things about writing from interviewing people beyond just the classroom. These people have experience that I don't yet have. Along with that they are more likely to look at a document differently, than myself, because In the past I have only written papers so that I could receive a grade. In the pas,t I have also only seriously written papers about historic events, novels, people,  etc. Unlike professionals who write about current news, court documents, medical histories. Interviewing a professional would give me another look at the world of writing.
Questions
1. What kind of person qualifies to be interviewed ?
2. How many interviews would make this assignment the best?
3. When should we pick who we want to interview by?