What resources come with a non-jr. show? What liberties do directors have when it comes to the script?

I'm a student who is directing a musical for my CAPSTONE project, and was wondering what resources come with a normal length show. I don't have an orchestra at my disposal, so cds with the music would be helpful but I'm not sure if that is just a jr. thing. Also, when it comes to the jr. version vs. the full version, are we allowed to either cut down a few songs from a full version (for appropriateness/talent ability) or add a few lines to a jr. version (to tell important aspects of the story that were cut)?