H1B Extension RFE

[ssmadurai]

My current status:

I am in 6th year(5 years completed) of H1B(this is my 2nd extension, I applied) and my I140 got approved in EB2 category and my priority date is May 07, 2010. My H1B expired on July 31, 2011 and applied for the extension on June 02, 2011(2 months before the expiration). Got the RFE on Jan 19, 2012 and it is regarding employer-employee relationship. USCIS required some additional documents on or before April 07 2012. Still my employer/lawyer not responded yet. Hope they will respond in a week or two.

Working at client place. Employer->Vendor->Client. I am working at this client place from March 2011 and the contract is till Dec 31, 2012. I have continues pay slips from the day of my H1 starts.

Questions:

1) Since I am almost in 240 days, is there any rule says I can't stay after 240 days of filing the H1B? Can I continue stay till my current H1B extension pettition is approved/denied?

2) How much risk is involved in this RFE?

3) In case of denial what are all the options I have to continue my status?

4) With my current query status, 240 days of receipt notice, Is it advisable to transfer to another employer with the condition of "Premium processing H1B approval"?

a). Is that mandatory to start for the new job immediately?

b). If I apply for new H1B, will it affect the existing H1B(current employer) status to denied?

c). If I get both H1B approval, shall I continue working with the current employer?

5) How much risk is involved in changing employer?

6) Some of the H1B approvals are coming without I-94 and we are asked to go to home country. What are the possibilities in my case due to 240 days completion?