H4 to H1B and H4 extension

[jessica233]

Hello,

Initially I was on H4 Visa.I have got a job offer and my employer has filed my COS to H1B in April under regular processing.Meanwhile,my husband's H1B has neared to its expiration and so his company filed his H1B extension along with my H4 under premium processing.Request your help in answering the below.

1.What would happen if my H4 extension gets approved after my H1B approval?

2.Is the COS to H1B still valid if H4 extension comes after H1B approval?Or do I have to go back to India to get my H1B stamped and start working from October?

3.How can I make sure that I go on H1B status from Oct 1st and that my H4 extension does not interfere in my H1B application?

Thanks in advance for the reply.