H4 to H1 questions - Need help

[kart1234]

Hi Experts,

Please help me with the below situation,

My employer is applying H1 for my spouse in this April and she is presently on H4 VISA in US.

We are planning for unavoidable trip to India in March and planning to return in May.

Is it necessary when my employer filing H1 my spouse needs to be in US? If she has to enter in to the US again, does she needs to wait untill her H1 approved & go for H1 VISA stamping or can she travel with H4 VISA?

Also if she is able to enter US with H4, does she needs to go for Visa stamping after the H1 approved in Sept or Oct?

Thanks for your help.