issues about green card

I am Ele... Few years ago I got the PRC green card. My husband is chinese we have 3 kids and I live in China for 18 years ,married for 20 years. As I know I try to get the green card two times.First time failed to get it. Second time turned away telling me that i need more documents.plus my criminal record was done but still want more documents so that the criminal record can expire,so u cant tak the green card. After I finaly got it after 12 years. Not easy to get this in PRC. My questions are:
1. if i am divorcing my husb do i lose my green card?
2. even i have a job no company wants to do the retirement procedures. So i worked 15 years here but no retirement anyway.
3.what advantage i have besides that i can stay in China without visa?
Thinking to return to my country ...