I have an approved I-140. I have elapsed my 6 years cycle before which I filed for my H1 extension based on I-140 approval. I am waiting for the approval of my H1 extn now. It was filed on Sep 12th 2012.
My husband is working here on H1 visa. He is not travelling to India.
I am planning to go to India during January 2013. If its safe to go, i will upgrade H1 extn to premium. My questions are as follows:

a. Is it safe to go to India (Chennai) for stamping? Will it cause any trouble?
b. If not, is Canada or Mexico safe to go for stamping?
c. Will I-140 approval help in successful H1 visa stamping?
d. Will carrying client letter be an additional advantage and avoid rejection or 221(g)?
e. If my visa stamping doesn't go successfully, is it possible for me to come back on H4 and transfer back to the H1 i currently have?

Please help.