Best place to ask all that sorta questions is in the presented discord chat. But for folks who are just lurking around here:
1: It is a fan run charity, that the folks at Desert Bus are very aware of. The past few years they have been announcing the prompt live at the start for us, and the discord channel we use is in Loading Ready Run's own server.
2: They have played the games before, but it is never something that is certain. Right now it seems rather unlikely since Watch and Play was the main place for them to be displayed, and Covid has put that on hiatus, but we never know what the future holds.
3: The main requirement is something linked to the Desert Bus Charity (be it the game, the live stream, or something else entirely) with a strong recommendation to use the prompt that gets announced. We have had remakes and reimaginings of Desert Bus itself, but that tends to be only the start. Management sims, RPG's, text adventures, minigame collections. Make what is in your heart.