URGENT- Travel to India with pending/approved H1B

[Sharvari22]

Hi
I am on H4 and filed for H1B this year, RFE is replied last month and now expecting approval in couple of weeks. I have to travel India by end of this month for some urgent work and I will be back in Jan 2013. My questions are

If H1B gets approved before I travel to India -
1) Is it mandatory to go for H1B stamping? Can I go for H4 stamping (my husband has changed employer this year so we both will be going for stamping) and come back to USA on H4.
2) Can I file for change of status from H4 to H1B again after coming back to USA and start work once it is approved? or do I need to wait till Oct 2013?

If I travel to India when H1B is in process -
1) What is the impact on the H1B process?
2) As told by attorney, it will abandon COS, but what about H1B? Will it also be canceled?
3) Can I file for COS H4 to H1B after returning from India on H4? or I need to file new H1B next year 2013?

Please mention if I have missed any other possible scenario here.

Please answer my queries asap, my travel plan is based on it.

Thanks a lot in advance. Waiting for your response.

Regards,
Sharvari