H4 expiring on May 10, 2014, but extension pending, and H1B to be filed in this year's cap. Can I apply for a change of status?

If H-4 is valid only until May and no extension is filed or approved, COS will most likely be denied.

Regarding H4 to F1 stamping at home country ?

Talk to the DSO. She should be fine.

How long does take from submit N-400 to fingerprint appointment?

Whenever there is a criminal conviction it is best to have a confidential meeting with an immigration attorney to discuss the facts and seek...

As a H1B Visa holder working for ComA, have LCA and I140 Approved. If I switch to ComB, Does ComB need to reapply for LCA again?

LCA is towards H-1b filing and Labor Certification is towards green card. You seem to be confusing the terms. Yes, the new employer has to start...

My daughter is marrying someone outside the US she wants to have the wedding here ?

Assuming your daughter is USC, she can petition for her fiancé to enter on K-1 to marry within 90 days. However she should have personally met him...

Will my wife have to stop working if her OPT expires (5 months) and we still haven't received her green card?

She should get an unrestricted EAD within 90 days from filing if you apply for it along with the AOS application.

Naturalized US citizen applying green card for sister who is currently in US in H1B!

It will not be a few years for her to get her green card through you. It will be a good 10+ years. File the I-130 and wait for the priority date...

Will B Visa still be valid if application for F visa is denied?

She can unless the B visa is voided by the Consulate Officer when the F visa is denied.

1) Sponsoring H-1B petitioner can petition when they have a job offer for you 2) There is no such rule

I140 Approved and my wife is applying for COS from H4 to F1 online through ELIS.

Your wife is a derivative beneficiary of the I-140. Both answers should be "yes." This is unlikely to succeed in changing status to F-l as she is...