Hi CJ,
I live in India. In Delhi. And I'll be happy to help!
Rabbit's tips are good but there is a lot of difference between North India & South India ....in regards to weather, culture and more.
The time frame you've mentioned is the Indian Winter/Spring. It's cooler, so you can definitely wear all kinds of pants. Infact, since you're a tourist and will be all over the place, I highly recommend pants of all kinds. By that I mean joggers, trousers, cargo pants and even track pants. Longer tunic length tops are great. Especially since your focus is the cultural/spuritual side of India; not the modern metro cities. Indians dress very modestly and like to cover their legs and arms and show bare minimal skin. Since you're coming in winters (or cooler months), this shouldn't be tough.
I like your capsule. Add to it jeans, tunic length tops, longer tunics and leggings, and you'll be just fine. Another point - clothing AND footwear is far far cheaper in India than in the USA, you can always shop in the cities. Also - scarfs. A lot of temples and poojas (prayer services) ask the ladies to cover their head in respect. But scarves are also much cheaper here and easy to buy everywhere, Incase you don't want to carry.
This year has been an exception and it was summer by mid-February. Usually it's much much colder (around 4 deg to 15 deg C) and I don't think you'd need sleeveless tops. Regular tops are just fine! I'll update you on weather conditions as your travel dates comes closer...
Since your trip involves a lot of walking, please bring very comfortable walking sandals and sneakers. If you'll visit lots of temples, slip on sneakers are a great option. India is dirty, the roads are bad, and you don't want to get anything pricey at all.
You can PM me with any questions. I have lived in North India (born near Rishikesh & Haridwar, very popular tourist spots for Ganges....and my parents still live there).
Hope that helps.