I am on L2-EAD valid - Jun 13, I am filing for H1 premium, if I am approved, can I continue work on H1 status before 1 Oct 13 ?

I agree with my colleague. You can work after 10/1/2013 if USCIS approve the H1B petition.

You have to file a Form I-485 and I-765 to receive a work authorization.

What options do I have if OPT stem extension is rejected?

If you marry to your USC girl friend, you could adjust your status even if your OPT STEM extension is denied.

How can I post an immigration question in immigration forum?

DACA related info is available here (www.uscis.gov/childhoodarrivals).

My husband had his interview in riyadh, i live in Texas, we are first cousins, marriege certifacete from india ,is that legal?

Texas prohibits marriage between first cousin. Although many states generally recognize marriages of first cousins married in a country where such...

Can an alien visiting the U.S. on a tourist visa have their child attend public school?

I agree with my colleague. Your child will lose his/her B2 status if s/he attend the public school.

H1B transfer and extension with new employer using approved I-140 of current employer, six months before exp of 6th year H1B

I agree with my colleague. It can be done, but it is not easy. After you move to the 2nd employer, USCIS could issue an RFE to the 1st employer...

I hold a work permit thanks to the deferred action given by president Obama . I need to emergency travel. Can I apply?

I agree with my colleague.

Can my employer apply for PERM while i work for him on h1b?

Your employer can file a PERM application while you work for the employer.

On what basis 30 days grace period rule apply ? from the day of H1B extension deny ? or I-94 expired date ?

There is no grace period for H1B. You will lose your status from the H1B denial date.