Job Change - Approved I-140 and other questions

[bluemoonromance 0]

So I had a few questions. I'm not sure if I was able to piece together all of this information looking through all of the other posts so areas that I am sure of I will clearly indicate below,

Background: I am currently in my 5th year of H1B with final expiry in October 2015. I have my I-140 approved as of November 2011 and have a PD of June 2011. I am currently contemplating a change in jobs and have some observations and questions with regards to the same,

1) My understanding is that to change jobs and apply for an H1-B three year extension, all I need is the I-140 receipt number. I have the receipt number for the receipt of the I-140 application but not the approval notice. Is this sufficient?

2) When the company I move to applies for the aforementioned three year extension to my H1-B, will it be granted for 3 years from the time of application or for 3 years from October 2015?

3) Let us assume I change jobs, leave company A (with which I have an approved I-1400 and join company B. They apply for a transfer and extension and everything goes well. Now for some reason if I choose to leave company B for company C in the next 1-2 years, would company C only be able to transfer my H1B for the period of the extension or would it also be able to use company A's approved I-140 (assuming it has not been withdrawn or revoked) to re-apply for a 3 year extension. Or would I need a new approved I-140 from company B?

4) Can company B use the I-140 receipt number to re-capture my PD or would it have to file a FOIA request to retrieve the actual I-140 application with approval?

5) Can the transfer+extension from A to B be denied/rejected/RFE'ed. Since at that point joining back with A would be fairly impossible (given I have resigned based on the receipt of H1B transfer notice), would the only option be to leave the country? Does this happen fairly often to recommend waiting for transfer to actually complete before resigning the current position?

I really appreciate any answers to my questions and I hope these help anyone else in a similar position

--blue