Supplement J

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.

I got my GC on March of 2016 through my then employer. Soon after getting my GC my project ended (May 2016) abruptly because of the change at client location. I did not had any project at hand so I started looking for a new job and started to work with new employer in June of 2016. There was no official end date of my employment with my previous employer through which I got my GC because they were looking for a new project for me but without any certainty how long it could be before they can find me a new project. While they were looking for a project for me, I already started working for my new employer so I just moved on without any official end date with my previous employer.

In Feb of 2019, I started a second job with another employer. Currently, I'm working 2 jobs full time on GC.

I am now eligible to file for citizenship through 5 years of permanent residency requirement. I'm worried if there will be any issues while I file for my citizenship because I did not stay with the employer that file my GC long enough after receiving my GC. Also will there be any issues because I am currently working 2 full time jobs when I file for citizenship?

I have a situation of my relative - person has the employment based green card received on Mar 12, 2012, Received EAD in 2007. However lost the job(job termination) (Nov 2, 2011) 4 months before to receive the Green Card. At the time when GC was approved (March 12,2012) person was not having the job, and there after person couldn't gone to job. Could you let us know what to do for GC renewal and for citizenship.