1. Are there any stamping dates available at Mumbai consulate in march 2012?

i hve same qus , i and got ans. i called vfs and they told me that there is construction work going on and they are advising everyone to take delhi to other embassy.

2. I applied for my H1B this year .At the time of filing the application I mentioned London as the preferred location for the Interview. However, I might be shifting back to India pretty soon and I may not be in UK at the time of stamping. Will that be a problem? Will I be able to attend the interview in India. Is there any thing that I need to do do shift the interview to some other location?

Hi you can attend to the interview in india. But you have to
show the residence proof and mention proper cause.

And if you want to you can also change the consulate,
but for this you have to talk to your consultant. But this
process is going to take 6 months because you need to write
a letter to your consultant attorney. and in turn the lawer
place a petition

3. Hi, my file has been selected in 2012 quota. Ive my file no. My consultant is not allowing me for stamping or interview till the market goes well in US. I dont have any other document except file no. can i go for stamping jst on file no. without knowing my consultant?

You need I 797 and DS forms and LCA to attend the interview.
Also you need many other supplementary documents like wage
certificates, IT returns of company which can be provided by
your employer only. Dont take the risk. You dont want to
ruin your chances for good.

4. In the h1b document they have mentioned the interview location as Chennai by that time Hyderabad office was not opened. can any one help me where i can attend the interview Hyderabad or Chennai and is it the right time to attend the interview?

i think u have to visit the same consulate as mentioned in
your h1b approval. If you want to change the consulate then
u have to get back to USCIS which will take around 3/4
months to change the consulate area.