Hi,
First of all, you should obviously explain to the university that you've only moved to the US recently somewhere in your application. (Perhaps in the extra information portion?) But that will not excuse you from the SAT/TOEFL requirements because even if you are an international student, there are plenty of people out there who speak/write flawless English. But always keep this in mind: universities aren't looking for people who're perfect, because those who are perfect don't need to go to college. While the language may be a drawback for you, give them no other reason to complain. Do well on your math, extracurriculars etc. Since you live inside the US, you have great opportunities that aren't open to students elsewhere, make the best of it.
Next, read!

Read EVERYTHING! From crappy novels to serious magazines to sports illustrated. It doesn't matter if you don't understand everything right away - it'll take time. But keep at it...Watch movies with sub-titles. Listen to songs, watch tv, use the radio. To start you off, in case you haven't already, I suggest granta.com/extracts. Granta is a literary magazine but most of the stories are written very simply...no fancy words, only fancy stories. it might not be available right now, but the site should be up and running soon. Some of the stories are free, so you can read those.
To improve your vocabulary, try cross word puzzles. Become a member at a library and look for books like Words to the Wise and other vocabulary-building books. Use them everyday...but don't start all of them at the same time. Start with one that you're comfortable with and work on that book. You have time, trust me. The Internet also has some great websites that can help.
http://flocabulary.com/wordlist has a lot of words, but remember, that none of these so called lists are complete - they don't contain all the words.

But you don't need to know all the words either. Once you start practicing the CR section, feel comfortable with the questions and start making good scores, you know it's time to take a break and work on the words you already know.
For writing, your essay has to be short but it must contain many examples from history, literature etc. So make sure you read up on some literary, political, historical figures. But you can use any relevant example really in the essay, so don't memorize the whole history book! :P Finally, practice writing everyday..get a blog! (or the old fashioned diary)
All the best...I'm glad that you're starting out early. It's really mature of you and I hope you will make it. Sorry if I sounded too preachy though...

I get carried away sometimes.
All the very best!