Agree with the above. A polo and khakis is fine too. You don't need to wear a suit or a JROTC/Sea Cadet/CAP uniform, cadets will actually prefer that you don't. I still remember the kid who came my freshman year in a full business suit complete with a pager as well as the kid who showed up in his CAP uniform as a Cadet Major (or something like that) and told us not to worry about saluting him. Really?
Don't quote me on this because it might be earlier but I believe the program ends at 10 or 11 on Friday, definitely no later than that. It takes about 45-50 minutes to get to PVD airport. Its a straight shot up 95N.
Maybe Objee can help out with the exact time.
I'd say 45 mins - 1 hour. There are a couple areas that slow down a tad, but in generall, it's moving at a good clip.