I don't believe you need to "buy" and "wear" a suit to this meeting! Simply look representable and have fun with it. The goal of this meeting is to introduce yourself, demonstrate your motivation to the school and get some of your questions answered.
Since this meeting is unofficial and informal, there is absolutely no need to dress up. Don't show up in a Budweiser shirt and cutoff jean shorts, just look presentable. Don't get too serious about it.
Things to bring:
1) your transcripts
2) your DAT transcripts
3) your personal statement (if you have it)
4) parents (if they have questions also)
Things to ask:
1) scholarship availability
2) what type of applicant they look for (do they emphasize on DAT or GPA more, x amount of time to shadowing dentists)
3) clinical experiences (how early do you see and touch patients)
4) how did their seniors do on their SRTA (Southern Regional Testing Agency) licensure exams (passing rate for 1st time takers)
5) How many seniors end up specializing (what percentages)
6) where they rank in NBDE Part 1 scores
7) Research opportunities
8) Clubs and organizations availability
9) with showing him everything you have that day, "what can I do to make or maintain my competitiness as a future applicant"
10) Can you spend a day in the clinic with an upper classman for a day
11) New technology? Do they have digital radiography yet, do they use laptops, do they have DentSim (virtual reality restorative machine)
12) ask for a thorough tour of the facilities (if not given)
If I guess right, your meeting will not take longer than 15 or 20 minutes at tops! These informal meetings are usually pretty short. If you get the tour, then you'll have more time to ask questions. I know you may have a ton of questions to ask, but try not to overwhelm the guy as he can get annoyed (I don't care how nice the guy is, we, human beings, always get annoyed)!
Your mission and goal for this meeting is simply to demonstrate your motivation and dedication for this particular school. Good luck and don't be nervious, they can pick that up very easily!
I've met, spoke to, and have written to many dental admission coordinators/deans/directors in my life and now I meet/talk to/write to many OMFS residency directors, there's nothing to be afraid, you're just that much more focused.
One last thing, smile, not a "perma-grin", but smile to show you're interested.