Topic: H1B to H4 In USA or Out of the Country .. Urgent Please Reply !!!

Hello Freinds, My Wife is on H1b which got approved on Dec-31-2014 and she is not able to find a project until now . Her Employer now wants to revoke her H1b. Below are my Questions .. 1. How Much time does we have to file the COS when he starts the revocation ? 2. How long does it take for the COS from H1 to H4 can i file this while staying here in USA ? 3. If she goes back to india and book an appointment at the consulate for H4 Visa is it sufficient or need to file a COS from india and then book a visa ? 4. what other options do i have converting her H1b to H4 ? Thanks a Lot and Help Much Needed ..