What is the quickest way for a Naturalized US Citizen to sponsor Green Card for his younger brother who is above 21?

I concur with attorney Behar's answer. Brother needs to explore other, much more quickly realizable options.

H4 extension filed separately and after I94 expiry. Messed up by attorney. Spouse got extension, H4 still pending.

This type of lengthy fact pattern requires a private consultation with a lawyer.

What can I do? Is it an USCIS's mistake?

I agree. USCIS rarely, if ever makes such "mistakes". Check what you typed in on that I-130 again.

What documents are needed to apply for tourist visa from China ?

I concur. Consult with an experienced attorney via Skype on sister's behalf - before she does anything with the US consulate.

What should i do when my parents wont transfer my social security income to me even though I'm 19 and graduated.?

There is nothing to do with immigration law in this question.

Don't you have an employer's attorney properly advising you?

How does a No Show case/deleted NIV application affect my F-1 application?

That one is too remote. Should not have any effect now. Be truthful and disclose.

H1B Dropbox Administrative Processing?

Consult with your employer's immigration lawyer on this one.

Should I file an I-90 with a pending I-485 if the immigration officer tells me I haven't abandoned my status?

Need to review your entire immigration history to be able to meaningfully opine.

How can I change my status from B1 to J1 while in the US? (PhD student)

Don't even try to change your status here in the USA - not worth it. Briefly depart and ask to be readmitted on your J-1 visa. Much cheaper.