I have a question on Extension of Visitor Visa, if anyone has passed thru this situation (I hope many).

It appears like the Current Processing time for Application for Extension of visitor visa is lagged almost by 7-8 months.

If anybody on Visitor visa B1/B2 wants to extend their stay for 2-3 months, even if they apply for extension, they will not be able to get final decision from USCIS. After expiry of first six months of stay can a visitor stay legally with a receipt notice??

What happens when returning? What turned back at airport as I-94 would have been sent to USCIS along with extension of stay application.

If there extension is not approved for a person staying with receipt notice beyond first six months expiry, will he/she will be considered illegal?

Will there be any problem to travel back with receipt notice (Visa-5 yrs multy) via airport like London?

Please advise. Thanks in advance