Should you dress up? Most people wore a suit and tie (or suit for the women). I would say how they were dressed was the least memorable thing about the interview unless it was extremely casual. I would recommend dressing up for the interview.
What's the best way to present your work? It was best when the interviewee came prepared with a short overview of their research. One thing that surprised me was how little some people came prepared to talk about things they wrote on their résumé. Least effective interviewees were ones who wouldn't elaborate on what they did, what were their duties, etc. IMO, shorter, concise resumes are better. Some people had appended other items.
Cultural differences: I interviewed both chem engineers and chemists and I noticed a big difference. The Chem Es all had some kind of industrial experience, either internships or actual business classes. This was very rare in chem students. Chem Es were also more clear in their duties, like saying they supervised these people, they were in charge of this group duty, etc. I'm not sure if this is a chem/chem e cultural difference.
What distinguished the students who got it right from those who didn't? The ones who got it right had more things to talk about than just their research. The ones who got it "wrong" we're unable or unwilling to elaborate on things or were perhaps a little too honest (like admitting to hating certain tasks which would be a big part of their jobs.)
Any other general comments? As far as other advice, I'd recommend trying to take interview training, I think that would help some a lot. I'm also rather indifferent to the follow-up thank you email but I suppose it couldn't hurt.