May I ask a question about F1 apply EB-2 NIW? Thnaks a lot!

I am currently F1, and thinking about apply green card through EB-2 NIW. I am worried about loosing F1 status if application is rejected. So should I only use F1 visa to enter US or do not leave US after F1 visa expires? (since F1 visa only valid for one year) Can my parents come to US while I am waiting for approval? Any suggestion about this kind of situation? Thank you so much for your kind help!