India

I'm considering a four week trip to India towards the end of the year (Sept/Oct/Nov) and have a couple of questions, hopefully someone who has been there would be kind enough to share their knowledge and experience

I'm very interested in spending a bit of time talking to people and building up a rapport rather than just being another foreigner hanging around the tourist traps.

I like the idea of flying in to Delhi and then traveling by train to Varanasi, Kolkata (where my father was born), Darjeeling and then back to Delhi to fly out again. Are the any other locations along the way that are simply a must-see?

So far my research suggests you can live comfortably on around $35 USD per day (for accommodation and food). Does this sound accurate?

There is so much to see that it is hard to suggest what to do and where to go. Google UNESCO World Heritage Tours. There are many sites shown from India and 360 degree panoramas from different locations. I have spent over 6 months there over many trips and still think that I have not seen anything. A rail pass is a really good deal and rail travel is a really good way to go. Airfare can be quite reasonable because of heavy competition.
You should be able to get by on that amount but have extra available. I have spent from $2 to $200 per night so there is a great range of accomodation.

Enjoy!