First of all, do you have Boot9Strap installed? If so, you probably don't need Emunand. Also, I think if you were to use a 2.1 Emunand, you risk permanently bricking your n3DS; the 2.1 sleep mode brick is probably an MCU brick from what I've read, and as such you can't recover from it, even with ntrboothax or a hardmod.
If you don't have Boot9Strap, you should follow this:
https://3ds.hacks.guide/
Or if you happen to have ARM9LoaderHax, then you should really upgrade to Boot9Strap now:
https://3ds.hacks.guide/a9lh-to-b9s
And about cheat codes, I think the latest nightly of Luma3DS has a Gateshark code loader built-in to Rosalina, but it's kind of buggy.