How exciting for you. I took my 2 year old on a 24 hour plane ride and he did really well. fortunately the plane seats had little tvs on the back of them so he could just stare at that for hours. You will hopefully have that as well. Water water water-make sure he is hydrated-this makes a big difference in terms of jet lag. bring snacks and books, drawing materials, some of his favorite little toys-if he likes trains or cars. Take off and landing is the tough part because of the ears-give hime something to suck on and before you go, teach him how to make a face like a silly creature so that he can try to unpop his ears if they get clogged-you know, hold your nose and close mouth and blow. I think he is too young for gum but I cannot remember that age anymore!
once there if you are staying in a nice hotel then you do not need to worry about the water there but just make sure you wash his hands all the time-bring plenty of wipes. Be very careful with street food for him-even ices or ice cream. no ice in drinks outside of good restaurants and your hotel.
I am sure he will be so fascinated by it all-the colors, the languages, the smells-just point things out to him all the time so he sees it as much as possible.
Things to do-I took my kids out to a place where they could take elephant rides, river rides on boats (we were in SE Asia) and that was one of the most amazing experiences of their lives-I am sure this is possible in India.
Temples-all those colorful images, paintings of Ganesh-kids love it-we did that and my kids would put the incense in the pots, put garlands on shrines, look at these massive Buddhas-it was all eyeopening-even for the baby.
I personally would not take much clothing-they have great material over there and clothing is cheap.If you have any articles of clothing that you realy love and want to have copied, bring it and a tailor can make it for you in a few days. That is me-I would make sure I had plenty of shopping time there! You will need a cotton long sleeve shirt and pants for him just in case there are alot of mosquitos. But I also bought those over in SE Asia for my kids because that is exactly what they have=suitable lightweight cotton clothing really good for protection. I am sure you will have a pool so that is a good activity to wear him out.
Kids are so adjustable and open at this age-you can have a great time with him. I am envious-I really want to go to India and so does my 12 year old son! Have a great time.
L. Schnall