Hi! Apologies for the suuuuuper late reply, there was a bout of life happening on my end.
What category to run is what category you like. NG+ Is definitely the easiest, but requires work to unlock - star rank on the pilots you want to use so they start with twin blasters, and all coins on the difficulty you want to run so you can start with the secret base and the homing shot. If you want to just dive in and start running, run New Game. I'm the only 100% runner currently, which entails getting all coins on a given difficulty, so feel free to drop me a line if you want to do that.
The only glitch that I'm aware of only affects Expert 100%, on the right side of Astropolis it is possible to die while running into the wall and pick up the Pepper Coin during the ship exploding cutscene. Other than that there are minor things, like landing a double hit on the first phase of Andross while he shakes by firing fast enough, but that isn't consistent given the inherent lag in the game.
SNES Mini is the only allowed platform. Record away!
If you'd like, the Star Fox Squad Discord is where discussion happens, and I'dve seen this a lot sooner there. Here's an invite link: https://discord.gg/0ZumT4PFmqz6AXtS
We'll be excited to have you! Expert is where most of the runs happen - I'm currently grinding Expert 100% in preparation for Completithon, I'm running it May 23rd. It'll be good to see some new people!