not sure what the method is that you are asking for on ps3, the way to play on ps3 that is allowed would be by having a disc and playing it on ps3 - not sure if your method would make use of the same built in emulation by sony.

either way though, ps3 is slow and your best bet would be to run on duckstation. default settings should be fine iirc, you just have to enable display options to show your settings in the bottom right of the screen (settings > display > on-screen display > show settings overlay).

no.

Anyone can get that glitch to work, it works consistently as long as your loading times aren't as slow as on unmodified first gen consoles. It's just that hardly anyone bothers running NG+ categories purely out of no interest. I myself like NG+ but most people just prefer running regular categories.

also edit: feel free to run NG+ categories if you are interested in them, they are fun and like you already said, essentially that idea you had

PS3 is the slowest console, Xebra is the slowest emu. (I love how these are so slow and bad to run on that they are just forgotten almost.)