a copy of the piano reduction will be the most useful to you, since it is very possible you will need music not in the vocal reduction (there are usually light cues in the midst of dance numbers, for example, but the music for those are not included, or only as "x" bars with no vocals, in the vocal score).
Cut/pasting (literally) works for me - and then I xerox the cut/paste so the page is clean. But that is because I, too, read music and it's easier for me to tie a cue to a note in a measure. Those who don't often make pages of counts (1 2 3 4 5 6 7 8 in lines, over and over again) and use those for cues within dances or insert/paste those into the libretto for their clean books.
Good luck!