This question has been asked a few times.
The answers:
1. Nobody knows he exact GMAT algorithm and the GMAC claims that by spending more time on the first 10 questions, you won't gain anything. However,
our tests with GMAT Prep prove them otherwise. Granted that GMAT Prep is not equivalent to the official test and that GMAC wont' release the algorithm, it is hard to figure this out, but a few logical conclusions tell us a few things: 1) if you spend extra time on the first 10 questions, you will have harder time with the rest 2) if you going to miss any questions, make sure you don't miss the first 10. See this post as well:
how-does-the-gmat-algorithm-work-120297.htmlThe best suggestion for the GMAT is to get as many questions right as you can so that you can get to the harder questions faster which guarantee you a higher score
2. Since the cost of questions is very high esp. for hard ones (thousands of dollars per question) and the test changes every 30 days, economically GMAC cannot produce an equal number of easy, medium, and hard questions, thus I concluded (no evidence exists of this however) that the majority of the test will have medium and easy questions. That was my experience after the initial barrage of the quant, the mid-section was fairly linear mid-level. However, I have no proof and we can debate about this for a long time and still probably not be able to contribute or improve your score by a single point.... so again, the main point is - get as many of questions answered correctly as fast as you can and worry only about the questions you see - one question at a time. Don't worry about what's coming.
Good luck!