Regarding my petition

You should be okay as long as you filed it before your I-94 expired.

Can I leave US without the result of my I539 application? Or is it better to wait for result, even after the requested date?

You have an option to leave if you'd like. Just make sure that you send in a withdrawal request to the USCIS along with a copy of your return tickets.

You might want to consult an immigration attorney in private. You can always refer to the filing instructions available on USCIS website.

Best possible outcome is to wait till you become an US Citizen and then apply.

My sister was refused immigrant visa last year. Now being asked to resubmit updated DS260. Does she have to pay visa fee again?

I agree with the answers above. She will need to pay the DS-260 fees again. You should be able to update the DS-260 and hit submit or file a new...

CBP usually updates your I-94 when you enter through a port of entry. You'll just need to give them your latest H-1B approval. Other than that, you...

If you are referring to a USCIS interview notice, you can most definitely call them or sent in the notice asking them to reschedule the interview....

Do I need to pay biometric fees for H4 EAD Extension? If yes, do I need to pay while filing I765 or only when USCIS notifies me?

USCIS notifies you about the incorrect fees by rejecting your application. It is better to consult with an immigration attorney and file with...

It does not. You're H-1B approval depends upon your and your employer's qualifications.

If you are doing a one step filing, you'll need to submit separate fees for I-130's and AOS. One envelope with all the correct fees (one check or...