Lots to cover here. Thanks to the others for their input. I’ll just add a few comments.
First of all treat this as you would any job interview. How you look, act, dress, speak etc are all going to be important. Dress very nice, but maybe not a suit and tie unless you are going for upper management somewhere. I’m guessing most won’t be in a suit. You want to portray yourself as a positive hard worker that can benefit the program. You don’t want your dress to say otherwise. Ditch the piercings for the interviews. Force people to look at you and your abilities and attitudes not your dress.
By all means get in touch with the recruiter from your school before you go down. Then see him again at the fair. It might not get you an in but you might get looked at a little harder if they remember you.
I’d mention the arctic research connection and nsf connection in passing to everyone. Who knows it might help land you one of the science jobs. It won’t help you be a DA.
What will help being a DA is that you’ve done it in the past. If you get looked at be prepared for a multi hour phone interview about your previous experience. Being a DA is grueling. Most hate it. Some don’t make it through the season. Washing dishes is far harder than most people think. On the other hand people who have done it before and know what they are getting into generally do OK. It’s a great way to get better jobs here, because all of the people you talk to will see you in the dish window. If you are bright and cheery as a DA you’ll do fine elsewhere. Last summer one of the DAs trained in the power plant in his spare time. He now has a winter contract as an operator.