Cross Buy is a feature that allows users to purchase a game once and receive copies for both the Rift and Quest platforms. For example, if you buy a Cross Buy game on the Rift store, you'll get it for free on the Quest store, and vice versa.
No, not all games support Cross Buy. It's a choice made by developers. Some games like Audica, Pistol Whip, and Vader Immortal are Cross Buy, while others like Beat Saber and Virtual Desktop are not. You can find a list of Cross Buy games at the VRDB website.
Yes, but only a limited selection of Oculus Go games are compatible with Quest. These games won't appear in your regular Quest library. To access them, you need to change the library in your Quest user interface from Quest to Go. More information can be found in the Oculus support documentation.
No, Cross Buy only applies to games purchased through the Oculus store. If you buy a game on Steam or the Epic Game Store, even if it's available on both Rift and Quest, you won't receive a free copy on the Oculus store.
Yes, if a game is not Cross Buy and you want to play it on both Rift and Quest platforms, you will need to purchase it separately for each platform.