Buying iphone in US

Hi, i am travellign to US next week and want to buy unlocked iPhone 7. While pre ordering it to my US address it's showing unlocked version under the 4 selected carriers only. My concerns are -

1) Can i buy a unlocked version here in US under any carrier and will i be able to use it in India without any hindrance?

2) Do it have international warranty? If not, can buying a apple protection care help?