When I took the test (2.5 years ago), we couldn't bring pencil/paper to the test station -- we had to use dry-erase markers and a piece of laminated graph paper (like a piece of whiteboard). There could be different rules at other test facilities, since the place I took the test wasn't solely a GMAT-testing facility.
Either way, I hated using the dry-erase markers for the math portion.
Yep. Just to be clear it's a piece of paper sized thing that is laminated and you have a pen-sized marker. It's not a whiteboard you stand at or anything.
OP: What is your undergrad and work background? Quantitative? Are you a native english speaker? If you have a quant background and are a native english speaker, you can do very well. It is more about brushing up and learning the test than learning new material.
My advice is to get the princeton review's "cracking the gmat" book (I don't work for them, I just used their book and liked it). It comes with some practice tests and a lot of practice questions, but the best part is it tells you strategies on HOW to take the test.
The math is, I would say, really hard high-school math. You don't need to know any calculus or linear algebra, but some of the problems are really difficult, especially when you have ~3 minutes on average to do them.
Verbal is tricky and sometimes obscure, but learn the strategies and patterns and you should do fine.
No one really cares about the AWA (essay writing), so long as you don't get a terribad score, but you have to be functionally illiterate to do really badly on it.