How long does it take for an H4 visa holder to have an H1B visa?

If he is subject to the cap, he will have to wait until Oct 1, 2014 to start working.

Be prepared to explain the scenario to the port of entry officer.

Couple of issues you will address is - (1) Will she be quitting her job, (2) who will sponsor your U.S. stay (3) her ties to her home country...

How to get H1B Petition number with receipt ?

Yes.

L1 to H1 COS confusion

Yes.

Employer can withdraw their petition. Depending on when they do so, it may/ may not affect your transfer to a new employer.

Applying B2 extension for my mom but my H1B extension is pending. Is this a problem?

You can mention that the extension is pending.

Can I sponsor my father for a green card even though he overstayed his tourist visa ?

Yes

Can I change my regular processing H1b petition to premium processing while replying back to a RFE?

Yes.

I recently married a foreign national with a tourist visa. Can she legally work in the US while seeking AOS?

If she works, it will be without authorization until the EAD is approved. However it will not affect the Adjustment Application.