1 No, fsr 3.1 can be run by anything, amd, nvidia and intel and if a game is fsr3.1, amd will free give it fsr4 for the new rx90x0 cards and maybe for the 7x00 series too in a near future.
2 the fake frames are unusefull in any games and the worst case scenario for those are racing games, fake frames = more lag, when you are racing and trying to do the best time, lag on your action is the worst possible choice so wrong example.
3 upgrade fsr is really just a little bit more than change a dll, the fact that you can enable it in many games with external tools like optiscaler will tell much about it.
@DarkNye87, use optiscaler for now, the only downside is the risk of a black screen after loading a new scene, just enter the setting, change ANY value (i usually change the triple buffering in double) of the graphics settings ad it will turn ok.
Still an official fsr3.1 support will be apreciated.