H1B transfer after stamping is done in India

[khushboo]

I have H1B visa stamping for company A before a month which will expire in 2015.
I still need to fly to US. I am still in India.
Now I got better opportunity in company B and I want to join company B.

So Company B needs to file new petition without h1b quota consideration.
Once the petition gets approved, do I need to go to the consulate for new stamping for company B or is it optional?
can I fly to US and work for company B using approved I797 of company B and stamping of company A which shows validity period?

Please reply asap...

[happybuddha]

Replied AAASSSAAAPP !

1. No
2. Yes