L1-A stamping required to start GC process?

You will apply for L-1A visa if you wish to work in that status.

I have changed my employer and have approved petition, my wife has h4 visa with my previous employer, Can she travel to US?

Yes, she can travel on valid H-4 visa.

What option do I have if PERM is not approved before end of Dec 2013. How likely will this happen? What options do I have?

It is taking over 6-8 months for PERM to be certified. Either address these questions to your lawyer retained towards PERM or talk to an...

Last time I entered the country I got a warning for long stay in Mexico. Can I lose my perm. residence next time I come back?

If you continue to "visit" the U.S. for couple of weeks and "reside" in Mexico for months, your GC will likely be revoked.

H4 to H1 - SSN and COS issues

Seek a full consultation to address your immigration issues. You are unlikely to get a reasonable response on the Internet as your question is...

COS from L2 EAD to F1

Yes, until she is informed of approval of change of status.

You are not to be a part of this write up. The "business necessity" is that of the employer and they are to assist their attorneys in putting this...

You can get the date corrected at a local CBP office.

H4 visa to L1A visa

It would depend on the reason for their denial.

My i-539 was denied for not submitting required documents, even though i did via registered mail. can i refile new one?

I don't believe you should abandon the motion and refile.