I want to get my SAT score up by about 150 by October, is this possible?

Yes, it is indeed possible. However, don't use Kaplan practice books or Princeton Review books. Use only College-board approved questions, and use the SAT Black Book to see your errors and revise them. Then, specifically, practice with Khan Academy to improve your weaknesses. As long as you have a dedicated plan, and you use only the best resources, you can improve your points by as much as you want. Also, try to gain more of an understanding of your high school material, as this is what the SAT focuses on, only the problems are more distorted than the normal ones.

I'm in the same situation, and I find that Khan Academy is really helpful for studying and practicing. They take your past scores and set up your practice so that you can practice specifically what you missed on your last test, and you can also take full timed practice tests. It's helping me get used to following the time limits and approaching the questions the right way. You got this!

Yes, absolutely! I experienced a roughly 100 point boost in my SAT score (from high 1400s on practice tests to a 1570--800R, 770M) after reading the SAT black book (https://www.amazon.com/SAT-Prep-Black-Book-Strategies/dp/0692916164), most of it coming on the reading section. It changed the way I approached the questions in an extremely helpful way.

Yes, that's possible you just have to keep on practicing and studying. Find what way you best study/review and keep on taking practice tests. If you find that you're better at the reading portion then try getting better at the math portion and visa versa. You can use https://collegereadiness.collegeboard.org/sat or Khanacademy.com to help you study.