July / August itinerary advice please

Hello I will be travelling to India with my wife in July for 3 weeks and am trying to focus our plans! We have both visited India before (Agra, Jaipur, Delhi, Himachal Pradesh, Bangalore, Kerala) and so would like to try some new places and stay as dry as possible during the monsoon. We like to see places and experience some culture but also have some time to relax. We are 30 and 29 years old and are happy to stay in some basic places but also like some nights of affordable luxury! We fly into Mumbai and out from Delhi. I spent 6 months in Bangalore in 1997/98 and so would like to return to the south - appreciating this is not the direct route from Mumbai to Delhi! Our preliminary idea is to head south for a couple of weeks and focus on Tamil Nadu as this is new territory for both of us before going north for our final few days staying with friends in Delhi. I have a few questions... 1. Is TN a good bet for avoiding the monsoon as much as possible? 2. Is it easy to book train tickets in the arrivals area at Mumbai airport? We arrive at 11am on a Sunday. The web booking process from overseas seems tricky! We would probably overnight in Mumbai but ideally don't want to spend much time there sorting out onward travel having spent too long in Mumbai on our last trip battling with Gulf Air. 3. Or are domestic flights with Jet, Spicejet etc the best way to travel long distances? These weren't available as much last time we were in India. 4. Is it viable to make a stop at Hampi en-route from Mumbai to Karnataka / TN? 5. In Tamil Nadu we are interested in Kodaikanal, Madurai, Trichy, Kanchipuram, Mammalapuram and Pondicherry. Any tips on these places, travel between or other suggestions? 6. Does anyone have other tips for relaxing (ideally beach based) destinations? 7. How easy is it to fly north from Bangalore or Chennai to Rajasthan (Jaipur or Jaisalmer) to have a few days there before getting the train to Delhi? 8. I would love to see Ajanta and Ellora but think that this would be too much given our time scale! 9. ATM's were fairly reliable in 2002 but we still took travellers cheques. Are TCs now a waste of time? I know this is a long list of queries but appreciate any advice people can give. Thanks James