H1B approved petition + H4 visa

I am working on an assignment in Houston on an H1B visa (valid till Nov
2014). My current employer is also planning to file an extension since the petition approval is valid till Nov only as well.
My wife who is also working for an Indian IT company also holds an approved
H1B petition , but her passport does not have the H1B visa stamped since
she is still awaiting for an opportunity to travel on the position her in
- Can she get her H4 visa stamped without affecting her approved H1B
petition which is valid till Dec 2016 ? Is USCIS authorized to cancel her
H1B approved petition based on her H4 visa application ? If she travels on
H4 visa to US and gets an opportunity from her current employer , does she
have to travel back to India to cancel her H4 and get her H1B visa stamped
on her passport ?

- Can she get her H1B approved petition transferred to another employer 
being in India itself ?

- If applying for an H4 poses a risk in terms of cancellation of her H1B 
appoved petition, I am planning to apply for a tourist visa so that she can 
travel here to the US for a shorter duration.Is that feasible ? If yes, what is the process of change in status from a) tourist visa to H4 b) tourist visa to H1B being in the US itself.

Yes, she can get her H4 visa stamped. It will NOT impact the H1B petition approval. USCIS will NOT cancel the petition unless the employer requests to withdraw the petition. No, she does NOT have to travel back, she can apply for a Change of Status from H4 to H1B in USA and work for the employer.

- Yes, she can get the transfer. Read  [H1B Visa Transfer Options ](http://redbus2us.com/how-to-go-about-h1-transfer/)

- No, it will NOT pose any risk. She is fine to travel on H4 and do a change of status, if she gets a opportunity at her employer. Do NOT complicate your situation by going for tourist visa.  Talk to your or your wife's employer's attorney, they will explain you the best option. You can also check USCIS website : http://www.uscis.gov/i-539


The current employer has not provided the approved petition copy to her yet.
But, they have given the EASC ** - petition application number. Is that number sufficient for some other employer to file for a cap exempt petition later on once she is here in the US on an H4 ?

The current employer will most probably withdraw the petition once she resigns there.
Also, the current employer does not share the approved petition copy unless they send her for stamping. In that case, is the petition application number sufficient to proceed for transfer to another employer or do we necessarily need a copy of the approved petition?