H1 to H4 - Change of status(COS) from outside USA

[anandselva]

Hi,

My wife is having valid H1B visa with A employer, but returned for good to India. I am currently working here on H1B.
Now she is planning to come back on H4 visa.

Clarification,
Whether she can apply change of status from H1 to H4 from India? If she can apply whether she has to go back for stamping.
Whether her H1B will be revoked, if she converts from H1 to H4.
Later, if she wants to convert back from H4 to H1 that will be processed as new H1B (i.e.) again she will fall under quota (or) again just Change of status from H4 to H1 is fine?

Thanks,
Anand S