Definitely ask for an extra pen. It can be a huge hassle to get another pen if yours runs out of ink.
This happened to be the first time I took the GMAT, I couldn't find the proctor and lost at least 60 seconds looking for him to request a new pen. After this happened, I took the GMAT a few other times, and requesting an extra pen at the start of the test was never a problem.
As far as the notebook, I would get a fresh notebook at the start of each section. But for most people, one fresh notebook should be adequate per section. I had a page or two left at the end of both the quant and verbal section. Just make sure to practice writing in an organized manner.
Also, if you need silence -- like I do -- they'll have ear plugs available if you request them from the proctor. This is another item that I requested more of at the start of each section.