Beinus

Hi, I am a green card holder since 1/31/2006. Now, I plan to work in China for a long period of time, say over a year. I want to submit N -470 to preserve my LPR sponsored by my own company which I set up two years ago. Is the company qualified to be the sponsor? Is it possible the N-470 to get approved? should I wait until it get approved before I leave US? how long would it take to get the decision back? how should the evidence letter be written? many thanks.