>>283748230
>Index needs 10 base stations
[spoiler]Only if you're counting in base 2.[/spoiler]
You just need 2, but you can use up to 4 if you're using 2.0 base stations and have a really large playspace or want better coverage.
>Rift doesn't even use any
Rift S and Quest use cameras on the headset for tracking. It's a lot easier to set up, but it can't track behind you and it's easier to block the cameras from seeing the controllers. Still fine in most cases though.