[Speaking to a POI in person - need advice based off of emails]

Here is the summary of the exchange I've had with my POI thus far:

Me: Sent interest email, asking to meet in person to discuss, etc

Him: Just come on by sometime and we can talk about grad study.

Me: What time/day works for you

Him: Tues/Thurs/Friday 9-6

Me: I'm stopping by on Tuesday at 3:30, looking forward to it etc

**Stopped by at 3:30 to learn he was in the meeting for the rest of the day

Me: I stopped by but you were in a meeting for the remainder of the day. Would Thursday at 12:30 work better for you, let me know. Thanks.

My question about this exchange is, what to I do if he doesn't respond to my last email. Do I go anyway? I don't want to be too overwhelming. Additionally, how should I treat this meeting? Full interview attire and resume or what. I'm very nervous, because this will be the first time meeting with a POI. What questions should I come prepared with and to answer? Any advice will be appreciated.