Sounds like an awesome experience for you guys! Enjoy it! : D
+100 to what underjammer has said. I am an Indian (although right now in US for studies) and what he has said should give you a very clear picture of what to expect - the positives and the negatives.
I would emphasize that in "urban touristee" areas you shall be better (much better off) off carrying a good point and shoot (G1X, G12, S100, S95) rather than a DSLR. Because,
1. It will catch much less attention.
2. Walking through crowd will be easier.
3. You will probably not get any artistic photo which requires the quality of DSLR in those places anyway.
However, keep you DSLR for your (probable) trips to the scenic places (the Western Ghats, The Himalayas, The Nilgiri, Rajasthan, the historical (non-urban) sites, the parks and sanctuaries, and may be if you have the opportunity to Arunachal Pradesh in the North East; and some more). In this scenario, I will strongly suggest 70-300L rather than 70-200L. You might find the second one to be quite limiting in reach even with a cropped sensor.
Enjoy your stay.