K1 visa revalidation

He should go to the Embassy and ask to get a new K-1 visa.

Your plan has far too many risks. Travel to a different country or wait until you are a citizen to travel there.

Does it matter whether i can get a job or not in my home country for my J1 waiver? better to say yes or no?

Cannot possibly answer your question without sufficient information being provided first. Best bet is to meet with an immigration attorney in person.

The employer should be paying the prevailing wage when the job starts.

Filing H4 EAD while Spouse’s H1B amendment is in progress

It appears that your spouse is eligible for the EAD. However, talking with the company attorney is the best way to find out.

If I have studied two semesters on A1 visa and one semester on F1, am I eligible for OPT authorization?

Go talk with your school's designated official for SEVIS matters.

No it does not necessarily violate your status if the company allows maternity leave.

H1B extension and I-140/I-485

It is time for a phone call or visit to your company's immigration attorney - he should be able to answer all of your great questions.

NOIR on original H1 while Amendment in progress

You can be quite out of luck if it is revoked. Get to a lawyer now to discuss options.

In case i could not apply for H1B this year which is my last chance and If i apply for EB2 NIW (i 140 and i 485) and get the emp

You really should consult with an experienced immigration attorney to determine your eligibility for the EB2 NIW.