How do I train?

What does the battery saver do in PokemonGo? Is there a maximum player level? Are there Legendary Pokémon available now, in the wild? I caught an Eevee, which of its evolutions will it evolve into? What happens when I tap the map? Can I catch shiny Pokémon? How much data does Pokemon Go use? What does the size of the multicoloured circle mean? How do I get Pokémon Go to detect my phone's orientation? How can I find Pokémon Go's uptime? Is there any advantage to joining one team over another? How do you heal in Pokemon Go?