miami in general: questions

Ive been accepted to miami and will be attending next year. I was just wondering what miami is like. Ive heard greek life is pretty dominant. Is that true or is not joining a sorority not a big deal? Do most students attend hockey/football games or is it not really that big of a deal when its game day? If you chose not to dress really preppy (since miami is jcrew u) will you be sort of "on the outside" so to speak?