Do you have a particular region that you are looking at? I think that it will be important researching the various regions of the US, as the climate, topography, and people vary GREATLY. The best advice that I could give, coming from a school with a very high % of foreign students, is to take it slowly. Fluent or not, American universities can be merciless - you will likely encounter TAs who are also foreign, but who you cannot understand - realize that you will be in hte same boat as others. I would advise partying a little, get the full experience for what this will cost you, but yea as the others said, make sure you stay on top of things. American students are typically preoccupied in partying, this makes it easier to ride curves to an A as well since you simply have to do better than the masses lol. If you decide to look at school in NY or even New England, let me know, I have a lot of info and recommendations
To answer your direct questions:
1. Yes take the SATs
2. Interviews are a joke unless you are applying to a top tier school (Ivy, Stanford, Tulane, MIT, etc)
3. It may sound gimmicky, but I am not sure how much other schools weigh foreign students, so write about a struggle, idolize the American way of life (I gagged even writing that)
4. Research some of the departments/professors at these schools. If you know what you want to study, have an idea of who the people in the department are. Getting to know and befriending professors is invaluable. Not only can it help your future, but from my experience, they are more fun than making friends with students lol I would imagine that especially as a foreign student, professors would be more willing to take you under their wing, so long as you do well