Form I-140

Previously I was on H1B when my I-140 was approved. Currently I am on H4 status, not employed and my priority date became current.
Previous employer has provided Supplement J and I have filed I-485, I-765, I-131 concurrently. The Supplement J indicates (#9 in Part 6) I am not currently employed with the sponsoring employer.

Q1) Upon receiving AOS EAD, can I directly join a new employer after 180 days of pending I-485 if sponsoring employer doesn't have any open position?

Q2) Can I start searching for new job before 180 days of pending I-485, but join after 180 days? Or, I must have to start searching and interviewing for new job, only after 180 days?

Q3) At the time of filing AOS, my Supplement J indicated that I am not currently employed with the sponsoring employer. If I join the sponsoring employer upon receiving EAD, then do I have to send USCIS new Supplement J indicating that I am now employed with the sponsoring employer, knowing that it might take a decade for my Final Action Date to become current and I may not be employed with the sponsoring employer at the time of GC interview?

Q4) What if I need to change my employer after GC interview, but before receiving GC?

Q5) I heard, after 180 days of pending I-485, even if I change my job couple of times, I can take the Supplement J only from the employer with whom I will be working at the time of GC interview. But can I still send new Supplement J to USCIS from each employers everytime I change my job? Is that legally allowed? or, is there any concern? Because, it might take a decade for my Final Action Date to become current and within that timeframe I might have to change job 2-3 times.

Situation: I am on a cap exempt H1 with an approved I-140 more than 180 days and I found an employer who can file my cap subject H1 this April.

1. If the cap subject H1 is approved before oct 1st, will my new employment start date be earlier than October 1st?
2. Should I have to leave my current employer as soon as the other H1 is approved?
3. What if I don’t join the new employer until I find a project with them? Meaning, can I wait until after oct 1st until I find a project with them?
4. From your previous calls, I understood that if the new H1 is not revoked until oct 1st, I don’t have to go under cap anymore. Is that still accurate? Also, can you explain about getting a new I-94?
5. Should I have to go thru the GC filing all over again? 
6. Can I start working with new employer while continuing my current employment?
 

I am currently on H1B visa (3rd year) and a few days back I got my I-140 approved in EB-2 category. I want to know if I can change my employer and retain my priority date.

A couple of questions I have in extension to the I-140 withdrawal by employer are below. If I have I-1485 pending for more than a year via company A and I join company B using my EAD/AC21:
a. what will be the impact if Company-A decides to withdraw/cancel/dissolve the I-140?
b. Is there a possibility for a NOIR to occur on the I140 which had been approved in 2011? If yes what is the impact in either cases?

What are the measures I need to take in either case?

1. Is submitting consolidated returns and audited financial statements for a parent company and its wholly owned subsidiaries sufficient to meet the burden of proof for establishing the company’s ability to pay by a preponderance of the evidence?

2. Where an employee who is the beneficiary of an approved I-140 and is eligible for AC-21 portability ports to a new employer in the same or similar occupation, must the new employer demonstrate the ability to pay the proffered wage from the date of portability?

3. When adjudicating I-485 applications for portability-eligible individuals where the petitioning employer is no longer in business, does USCIS require the subsequent employer to satisfy both the ability-to-pay requirement and the bona fide offer of employment requirement from the date of the employee’s subsequent hire through the approval of adjustment of status?

4. Why are prorated net assets not sufficient evidence to support ability to pay?

5. Why is the Yates Memo not applied if a beneficiary’s W-2 indicates that the actual wage paid to him/her is at least as much as the beneficiary’s proffered wage for the prorated period?