Dont be afraid to ask direct questions about your specific application. "Do you think I have enough upper division sciences?", "Is my GPA/MCAT score competitive?", "Do you notice any strengths or weaknesses on my application that really stand out?" etc. Make sure and bring all your transcripts and a resume/CV. If you already have a draft of your personal statement, email it to them ahead of time so they can give you feedback at your meeting. Also, bring a list of questions/concerns so you don't forget anything!
You can also ask questions about the school and current students in general such as clubs offered and if a lot of the students do community service at a local clinic (maybe its a school requirement?). What kind of extra help is offerend if a student is having trouble in a class? What do the students usually do in the summer between MS1 and MS2, are their research and/or travel opportunities? Is this a good part of town? Do most of the students live nearby? While these types of questions are not about admissions I think they show a good level of maturity. You are showing that you want to get accepted to a school that is a good fit for you and not just any school that would take you (ok, the latter might be true, but you dont want schools to think that!) These types of question will also be helpful because for many schools secondary application, you must write why you are choosing this specific school. The more details, the better!
Don't freak out too much about your appointment! I think the most important thing is to look nice and be prepared!. I think jeans are ok as long as they're nice (I wore dark jeans, flats and a cute cardigan to my meeting). The main point of the meeting is for them to point out any red flags or negativities so you can try to fix them or make sure to clarify them on your written app and to get your name in their head so when they going through the interview files and come across your name, it'll look familiar.
