I'll try my best to answer all of your questions!
1) All of your official GMAT scores are available for business schools to see (as long as you do not cancel them at the end of the exam). When you select to view your score, your score becomes official, and you cannot cancel it. That said, you certainly do not need to worry about the schools seeing your lower scores- Business schools are only going to consider your highest official GMAT score.
2)/3) It sounds like you've been doing a lot of studying! I would highly recommend taking full-length practice tests (CAT Exams). This will allow you to work with new material, and practice the format and timing of the exam. I have added a free CAT to your account, and you can purchase 1-year access to the full set of CAT exams on our website for $49: http://www.manhattangmat.com/storeitems ... 81&catid=4
You can also gain access to a full set of CAT exams by purchasing any one of our 9 Strategy Guides for $26: http://www.manhattangmat.com/storeitems ... 19&catid=6
I hope this helps, and let me know if you have any questions!