Depends. If you're joining, you'll have to fill out a sheet, they sit you down, tell you what you need to being next time, and they'll schedule another appointment at a later date. If not, if youre there to ask questions, I'm sure they'll be happy to answer.
It's best to have an appointment though so you won't have to wait.
No, you can just walk in and whatever recruiter is available will help you.
Thanks! Your answer is awaiting moderation.