Although I can't say for sure (never hired anyone), I think the notes above about "Relevant experience" really hits it on the nail. Resume's have a lot of info on them, and are often short on details. You should explain to them what you've done that makes you ideal for that specific role. Don't talk about your life dreams, just keep it simple and direct.
On what to wear: Dress smart. If it seems like a fun place, dress a bit fun. In NYC, a nice pair of jeans, with a sharp shirt and jacket would probably be a really appropriate attire. I don't think i'd ever show up for an interview with just a t-shirt on, but i guess it depends.