I could swear I saw something that provides a place for notes for each instrument. (I.e., capo-location, which kit to use on electronic drums, etc.)
But now that I'm using the software, I can't find it.
Is there a solution for this?
I think custom fields would be the way to go for this. You can go to Repertoire > Custom Fields to add custom fields for songs, and you can designate which users will see each custom field.
That looks to be the winner.
Will those be visible in setlist mode though? These are crucial for performance.
Yes, you can add them to the song list or the song detail portion of the set list view:
http://www.bandhelper.com/tutorials/changing_layouts.html
YES
(https://media.giphy.com/media/uTuLngvL9p0Xe/giphy.gif)