I responded to this question recently and I thought you guys might find the answer useful. Hopefully some of you will be able to give some more info.
This link might be helpful: How to get free 1/250,000 and 1/1,000,000 maps covering the whole world?
Road conditions in India have improved dramatically in the last 5 - 7 years. Most of the main roads used to be 2-lane highways with no shoulders, and now they are well-paved 4-lane roads, making them much safer ("Safety on the road = Safe tea at home," as I read on one of their road signs!).
India is a land of extremes. Like just about everything else in the country, there are extremes in road conditions. I cycled on very busy roads, but I also cycled for long stretches of time, passing only a few cars a day (this was south of Mumbai trying to be as close to the coast as possible on the way to Karnataka). Heavy traffic can be chaotic, but vehicles aren't very fast overall, so I found it was not too bad. People traveling on the axis between Delhi and Benares often have a not-so-good experience. while people traveling south or up in the Himalayas seem to have a much more pleasant journey overall.
There are plenty of smaller roads that are very enjoyable to ride. As for maps, Nelles has a set of 4-5 maps to cover the whole country (1/1,250,000) and they are very good. Also, the Lonely Planet has a good Atlas that fits perfectly in the Ortlieb map holder (same scale).