Welcome!
The wonderful thing about going to BB shows/Expos is that ANYTHING GOES. Seriously. BB is a subculture that is based on physical appearance and many people will wear anything that shows it off. It is quite entertaining. You can't go wrong.
I've seen people walking around in thongs, lace pants, bathing suits, hot pants shorts, workout attire, jeans, shorts, really.....anything is appropriate. It is crazy.
BUT, to go to the actual show, wear anything...jeans, skirt, whatever. Wear comfy clothes and VERY COMFY SHOES to the expo. The expo is HYUGE and your feet get tired quickly. Awards show...not sure. I would dress in something that makes YOU feel good. Maybe dressy casual? Guys....slacks, nice button up shirt. Girls....nice skirt/top, dressy slacks and nice top. Think hot night on the town, but I wouldn't wear sequins or a prom dress.
Columbus is cold now. You'll need a jacket definately. Don't count on being able to wear a miniskirt around town. Dress warm. Not sure if they will have a place for jackets at the expo, so wear layers that you can tie around your waist.