Hello, I am not an expert although in my opinion here are the answer to your questions:
1) doesn't matter when you "arrive" in the US or "start a job" in the US, what counts is the date of the approval of your VISA, there fore a 9 months extension is not possible. However you will be able to extend it for 3 more years after August 2016
2) to renew a passport you need to register yourself as a resident in the US, then, you just have to go to the closest embassy of your country and they will renew your passport. I've done this procedure myself.
hoep this helps!