Creating An Additional Learnable Menu of Spells?

Thanks Madsiur. While the answers to my questions are frustrating, your assistance in understanding these limitations is incredibly helpful in that it allows me to move forward.

There's no easy way to add a new skill. Regardless of the path chosen, you'll have at least some menu work to do, in a battle menu and field menu. I'd suggest you try your hand at it once you get a bit of ease with ASM. You'll learn a lot!