Help me guys, I'm going to an interview this monday and i'm not so sure about what to bring and what to do.
I know the basic things like dress code, how to sit, what not to talk, etc2..

So here's the thing, I'm going to an interview for a private computer/IT/mobile apps/design-ish company and this company is the kind of company that practice casual environment (you know, no suits and ties kind of things). Oh and this is only interview for internship.

1) So, should I wear shirts, ties and khakis kind of dress or shirts and jeans better?
2) Is it neccessary to bring laptop to show all my works (designing skill, programming, all those computer stuff) or USB with all the works in it is enough?
3) Should I be funny and cool or smart and serious?
4) What else do they expect for internship student?
5) Sijil is important? I go to many competition but they dun't give sijil. How?