Why do you say American graduate students for nothing? You can read a blog directly! I know a girl whose background is very similar to yours, and she is also studying for a doctorate in statistics in the United States. You may be a little insecure! You have worked in Hong Kong, so English should not be a problem. Many foreign students I know feel that their English is not very good and they have graduated. With your professional background and work experience, it should be easy to apply. Get used to it in a few months or six months. You can also change your major when you come to America! It depends on what you plan to do, or whether you choose to go back to China or stay in the United States after your studies. I don't know much about remote sensing. You can talk to your tutor and see what the future prospects are.