There's an awesome open source version that seems to run perfectly fine, you'll have to provide the ROM and compile it yourself though. https://github.com/fgsfdsfgs/sm64pc/tree/switch
Ah okay. I remember a while back when of the homebrew apps received an update that kept the screen from sleeping. I think it was the classic version of tinfoil.
This streams from your PC. Lower clock speeds would just make it worse. The switch isn't actually running any games with this, it's only playing a video.
What do you mean? It's not locked at 60fps at all. If it is for you then I suggest turning V-sync off in the video settings in the game.
Edit:
Proof:
https://i.imgur.com/vMsmzmF.jpg