US Citizens do require a visa for India. You can request an e-visa on this website below. While this can be issued in days, we recommend applying 2 months early. Apply for e-visa here: https://indianvisaonline.gov.in/evisa/Registration NOTE: There are a LOT of private third party companies offering to fast track your visa, but please do not provide your personal information to them. Make sure you go through the government of India website mentioned above.
You should arrive in Chandigarh by the afternoon of April 12th. Festivities should be done by the afternoon on April 14th, so you can plan to fly out of Chandigarh then. Please let us know your flight schedule so we can prepare for your arrival!
Other than tequila, here's some information on suggested vaccinations. TLDR: At least Typhoid & Hep A, assuming you are up to date with all others like Hep B, TDAP, MMR etc. More details at this link: https://wwwnc.cdc.gov/travel/destinations/traveler/none/india
No. We suggest converting to indian rupees beforehand or ensure you get a travel enabled credit card to make life easier.