Changing address married to USC?

Yes, will considerably delay your case and USCIS may even end up "losing" your file.

Legal stay after i94 expiration?

Yes - as long as timely filed, can remain and continue working until a decision is issued.

Can I change employers with an expired green card but a ending citizenship application?

An LPR is free to change employers at any time or even not work at all.

Can an applicant applying for NIW/EB1 GC application leverage cross-chargeability if spouse is born in the US?

Don't try that one - will never work for your purposes.

H4 ext status delay

Hopefully congressional inquiry will bear fruit.

I have a valid O-1 visa but am not eligible for an FHA loan because I don’t have an EAD card. What can I do to become eligible?

Merely having applied for "NIW" or the like will not do -FHA seems to be requiring one to actually be an LPR.

Can I apply for the green card being J1?

As long as you are sure not to be subject to the 2 year HRR limitation, then yes.

Why persist on "NVC"? Aren't you eligible to apply for I-485 AOS?

H-1B Approved for COMPANY-B but don’t’ want to Join COMPANY-B.Instead of that want to Join COMPANY-C 

Can join whichever employer you ultimately decide upon. Will need to provide pay stubs of where currently working.

No big deal - happens all the time. Call the 800 number to correct.