Everyone has given great advice. I'll just add a couple of things to some of your questions.

2) The most common thing to wear for a "modern" city girl would be Jeans + a top or Kurti (a shorter length Kurta than what is there in a Salwar). Thats what my wife wears most of the time. A saree is definitely ultra formal wear (for weddings or special occasions). The other option is a Salwar-kameez but at least in my circles, a girl would only wear that if she's going to a family gathering and needs to wear something "traditional".

3) One of the best conversation starter for a foreigner in a new group of people is to learn a couple of local language phrases and try them out. Everyone will have a good laugh about it followed by trying to teach you more of their language.

4) Real maple Syrup from Canada. That is awesome. We mostly only get Agave substitutes here (unless you are willing to shell out some serious dough). Depending on the particular homestay, they may not have any idea what to do with Maple Syrup so maybe you should get pancake batter as well and do a whole pancake+maple syrup meal. That would be fun activity to do together with them and a fun way to get to know the people you are staying with.

Real Maple Syrup. Damn that sounds good. ^{Can I come? Please.}

5) Take a flight. Much much more hassle free and not very expensive. Like everyone has said, go by train only for day journeys under say, 6 hours.

6) There are different types of street food. There is the street food which is actually made "on the street" by a vendor. I am born and brought up in India and even I will avoid those unless its a vendor I'm familiar with. I used to frequent those stalls when I was studying but now I avoid them.

The best thing to do (which is what I do as well) is to go to a place like Haldiram's or Bikanerwala for vegetarian street food or Khan Chacha for meat based street food. There are fast food joints which specialize in 'street-food' but they are not really on the street. They have proper air conditioned seating and good hygiene standards.

If at all you decide to be adventurous about trying "real" street food on the street then there are a couple of rules I typically follow - No meat. No water. No uncooked liquids - e.g. I bring my own bottle of water and if I'm having Samosa or Wada Pav, I wont have the liquid chutney because I dont know the source of the water and its not boiled/cooked.