A quick update on learning to play my first arrangement:
There's a part in my arrangement of A Mighty Fortress Is Our God when I use the one and four fingers to play notes E and B, then three and five to play C and A, then back to E and B with one and four. It's a challenge for these cumbersome hands of mine.
Likewise with doing ASL (American Sign Language, something else I'm currently learning in my spare time). My fingers are slow doing numbers six to nine. Easy stuff for most people, but not for me (yet).