Can I get B1/B2 along with existing stamped H1B?

[abhiijit]

I have H1B stamped from employer A, and got an onsite interview call from employer B.
This requires me to get an B1/B2 visa.

1. Does it calls for cancellation for existing H1B?
2. In case of cancellation, can I go for stamping for employer A again if discussion with employer B is not fruitful?
3. My spouse has H4, will her visa be also cancelled if she travels along with me on B2?

I am currently in India and never traveled to the US, nor do I have prior L1/B1/B2.
Please help me with the queries. Thanks!