H1b transfer- EAD/AP on my hand

[Mahmad]

Hello Friends, 

I have following questions to ask you. I really appreciate if you can answer me. 

I have H1b since Jun 2007 with one of the Desi consulting company in New Jersey and applied for Green card in EB2 category on 2009. I got my EAD and advance parole (AP) in 2012. I got married after get the EAD/AP and my wife came to USA on H4 visa as I am working on H1b till today. I have valid H1b till 2018 and valid EAD/AP till April 2017. 

My wife is 100% house wife now and she is not interested with further study or job. 

I am on bench period last one month and my desi consultant company terminates me next one month if I am not able to get project. I am planning to do H1b transfer to different company. I have below questions to ask you, 

1. If I transfer my H1b to any new company, what is the status of my current EAD/AP which I got from my current employer? Will have to apply entire green card process again from new company? Will my EAD/AP card going to void? 

2. How can I continue my green card process with new company after H1b transfer? What documents required to continue my green card process with new company? 

3. I have H1b till Sep-2018 and have I-140 approved. I already passed 6 years of H1b. if I will not get my Green card till Sep-2018. Will my H1b going to extend next 3 years or not? 

4. What is the use of AC21? If I use AC21, Will my wife stay with me in USA? 

Thank you.