Parking can be an issue so get there early but do not GO IN too early they are specific about not arriving more than 50 minutes before the interview time. You will get your picture taken, as they mentioned in the email. What they did not mention in the email is that if accepted that picture will follow you for 4 years, so look your best
The process is truly set up to help you interview the school and for the school to interview you. Be yourself. Have a strategy for your essay. There will be a large clock on a screen and known you have 25 minutes so allot X time for an outline, and finish with X time left for review.
I was not asked to address specific weaknesses in my application, but I do know that others were asked this. Be ready to take responsibility for and explain anything that they may ask regarding your application.