Hi Tim
I kinda like the separate library viewer, but the S-Pad option I think would work. The TOC on the left comes in handy, although still irked about the alpha ordering of the titles
As far as developmentally, I am not an expert so I do not know how easy these ideas would be to implement, but a suggestion would be:
Like the other library search references, a radio button for "Other" or "External Library" or "Devotions" or "Books" "User Library" might be a way to go, then using the already available options on the tab page would work as far as All/Single books, etc.