Hi, what role, outside of formal interviews, do interactions with admissions staff and students have in the admissions process?

I've been to a few info sessions now and some of the students I've talked to hinted that it's important to talk to people.

How are evaluations/judgements made at informal events by admissions staff and students, if any? This applies for things like info events and campus visits. I got the sense that students recommend people to the staff, and the staff are always evaluating.

If that's the case, do you have recommendations on making this an effective interaction for both sides? Usually I've just been firing question after question, but really it's been from my own curiosity.

You are correct that any interaction with someone in your target school is an opportunity to make an impression. What would be ideal, is if your dealings with people connected to your school result in your being remembered by the committee so that you are familiar to them when the time comes to evaluate your package. Keep in mind that being remembered can work two ways, so don't be over-bearing, and know that how you treat others including your fellow applicants can be just as memorable for what you don't say as what you do say. In other words, be sensitive to the social dynamics and make sure you're not dominating or hogging time with representatives of the program, yet make sure also that you are being assertive and letting your personality shine through. Be positive--don't ever ask questions that could be construed as negative about the program. Save those questions for friends or consultants!