Will Green Card filing thru brother hinder my B1/B2 visits to country?

No not necessarily if you can establish that your trip is temporary through evidence such as return travel and itinerary.

Marriage or k1 fiancé visa?

Both applications have benefits and drawbacks and it is best discussed through a consult. Yes you will need to marry within 90 days of entry and...

When will do I receive the interview date?

It depends on the interviewing location but often can take 1-3 months.

Can I apply for a Visa for my mother inlaw to come help with the kids for three months?

Your mother in law must apply for a visitor visa on her own through establishing sufficient Financial and familial ties to her home country.

Do I have to put yes for where it says have you ever got arrested for citizenship ?

Yes you would need to disclose this but best to have an attorney review your background to confirm eligibility.

Provide a statement of explanation and formal request for expediting.

Is it necessary to file for I-765 while I-130 is pending for a student?

Not unless you filed for Form I485.

I-539 application filed for B-2 Visitor Visa extension. Paper receipt not received yet, I sent the application 21days ago.

You can check to see if fee was deposited by USCIS.

You should reapply but do so with the assistance of a lawyer.

I’m I eligible for citizenship ?

Any other trips outside US? Consult with an attorney for a brief review.