To be clear, it is not IndiGo (the Indian airline) that is purchasing F9, but Indigo Partners. Search 'indigo bill franke' to get more info on them. There isn't a lot of info on them, but they have a long history with LCC/ULCC airlines - Wizzair, Volaris, Spirit, Tigerair, Avianova.. Look through their offerings a little to get an idea of what expect, as they seem adopt each other's ideas.