I can commiserate since I emigrated from Russia.
Around my sophomore year I began preparing myself for the SATs. The hard work payed off, but it was a lot of it. MIT requires the highest SAT scores out of all the colleges that you have listed. Sending your ACT results might work to your advantage as it is more specialized and shows your scientific side, but it is my personal opinion that MIT would prefer SAT scores.
As for your low math score, that can be caused by two things. Either you are having a hard time understanding what they are asking, as is often the case with immigrant, or the math that they require is so simple that you have long forgotten it. You still have time to brush up on the material, I recomment Baron's SAT review book.
If you choose to leave your scores as they are, they certainly might deter you from entry. However, there is no clear cut minimum score. A lot is also based on your charisma and personality. In other words, charm their pants off.
I am typing this from my BlackBerry in class so forgive the long time between responses.