Had my son's (he's a minor) interview at O'Hare last week. There is a separate lobby waiting room. Strangely, they had FoxNews playing on the lobby TV and they were airing a discussion on the pointlessness of airport security and how it's now working and we're all at horrible risk. Slightly offputting to watch while sitting in the Homeland Security office.
While the waiting room is separate from the interview area, the interviews are done in a smallllll room that has 5 or 6 desks with officers all doing interviews at the same time. We were literally sitting < 4 feet away from the next interviewee with no privacy wall between. I could tell you where the person next to us lives, works, and travels to.
They asked for my state ID (not passport - to prove his address), asked him his address, and if he'd ever been arrested. And that was about it.