It sounds like the answer is “no.” If someone is in the US when an I-539 denial is issued, they likely have unlawful stay.

Most of the time they are denied if you miss biometrics, but if it was approved and you are sure you didn’t overstay, then you should be fine.

This should be fine on a B visa or ESTA.

Respond to it. It’s not uncommon for them to ask for documents they already have.

Yes, but you may not be able to adjust status if you do not currently have status. Speak with an attorney to analyze your case.

Generally you cannot work without work authorization, even if the position is remote and even if the position is on a volunteer basis. There is...

Unfortunately CBP has the power to do this and they have been doing it a lot with people in this exact situation returning after applying for a...

No, you would not need to list it in this case.

It would be easier to just file for a second extension in a case like this. She can file another I-539 if she needs to extend her stay longer than...

Usually this happens when you send some kind of letter or correspondence to USCIS after filing an application. I would have to see the details of...