On an H1b visa for 2.5 years and my employer is about to move me from full time to part time position (50%), am I out of Status?

That would be drastic cut in wage and hours = major changes in employment. Amendment should be sought.

Can I use the single I-539 to file for H1 and H4 together for my family

One form for both

Visit to India after applying H1

Change of status, if applied, will be considered abandoned.

Been 2 months since I applied for OPT, still initial review? And H1B has been filed while OPT is pending - advice?

If the H-1B is approved, the OPT will likely be considered abandoned.

Is AC21 required for spouse, if spouse is moving to different job on EAD. Primary applicant is still staying with same employer.

No. She is a derivative applicant

Employer A applied for my H1B. Got offer from Employer B who is ready to file H1B too. I am on OPT. Can I start with company B?

It is not a transfer. Company B will file a fresh H-1B petition in your behalf.

Can I extend my I-94 locally without going to Mexico/Canada ?

You can seek extension of your H-4 status if you continue to maintain status and your husband continues to maintain his H-1B status in the U.S.

My employer filed my LCA yesterday. How long does it take for processing?

About 7 days

Extension applications are filed with the USCIS. What status are you seeking to extend?

Converting from H4 to F1 and getting stamped on F1.

1) Home country 2) Not recommended 3) Could be rejected 4) Home country or country where the last degree was awarded