Third question: would either feature #1, #2 or #3 afford the following ability:
To be able to set both the *very topmost* staffline on a page (ie, the
top staffline of the top staff of the top system of the page) at an
exact vertical distance from the top of the page and the *very
bottommost* staffline on a page (ie, the bottom staffline of the
bottom staff of the bottom system of the page) at an exact vertical
distance from the bottom of the page? (The point being to be able to
make the topmost stafflines and bottommost stafflines align vertically
on facing pages (or to even more strictly force those distances
constant throughout an entire score.))