Sponsoring H4 to H1B

[KMRS]

I have an employee with H4.  We are willing to sponsor her H1B. 

1) Would she need to stop working (until approved) if an H1B application is submitted?  

2) Is approved, is there any limitation on promotion for employees on H1B?

3) Does applying for H1B affect her H4?

4) Anything else to be concerned about for her status?