The iPhone models currently sold on apple.com work with nano-SIM cards from compatible carriers. And they work on many 4G LTE networks around the world. Contact service providers for details.
Information on iPhone 7 and iPhone 7 Plus support for LTE networks by carrier and country
Yes, you do. When you buy the iPhone from apple.com, it is sold unlocked. You can contact a carrier directly to learn about the service plans available for the iPhone.
A portion of the proceeds from every (PRODUCT)RED™ purchase will go to the Global Fund to fight AIDS in Africa.