H1B extension RFE (Current H1B and I-94 both expired) . What is the out of status rule?

Hi, My H1B extension was filed in July 2012. Current H1B and I-94 expired in Sept,2012. I got RFE on my H1B extension in Dec , 2012. My employer is filing the RFE response in next week (Feb, 1st Week). I am concerned regarding the 180 days rule (for unlawful presence), does the 180 days start from - a. Date of I94 expiration or b. Date of current H1B expiration or c. Date of H1B extension denial (if my RFE gets rejected). Please advise. Also if I don't get any response for my RFE , does the 240 days rule will come into affect and I will have to go back to my home country and wait for the H1B extension result and I can't work for my current employer. Last question - My husband is on H1B as well, so should I file for H4 while waiting for H1B extension result?