GMAT Strategy

Okay, so I started preparing for the GMAT about a week ago and saw that one of the most difficult areas was critical reading. I essentially did all the problems that I could on the forums here and a few problems from the OG 10 book (about 30 or so).

I studied a bit for the math section, but not extensively (I'm currently in college and am getting A's in my math classes, so I hoped that questions on the GMAT wouldn't be as difficult to solve...). But particularly, I just wanted to take a practice GMAT to see how I would fare when applying to business school later on.

I took the GMATPrep Practice Test 1, and got:

Quantitative: 49
Verbal: 39
Total: 720

How accurate are these scores usually in comparison to actual GMAT scores assuming similar testing conditions?

Also, how do scores become greater than 41 for the quantitative section when there are only 41 questions?

Thanks!