I found the Recruiter I met her very helpful. He was genuinely interested in what I wanted from my next job and why I was moving. Agencies I've used in the past have only been interested in what I can do etc.
To prepare, I'd say be clear on what's important to you. What you do an don't want.
As a Recruiter, I did 2 interviews. Formal but not intense.
For candidates, interviews start with a phone call. Then a face to face with the Recruiter. Before meeting a potential employer, we meet candidates again to prep them for their interviews.
21 I think. Might be 22 and you get your birthday off.
Focus on the employed, not about the company