Re: margins - I'm not quite sure what you were going for, but my suggestion as per the help guide was to set the page margin value to what you want and set the (horizontal and vertical) text box margins to zero so that they fit snugly against the margins. What you have now is margins that don't represent the actual margins and the text not aligned properly. Compare before and after:
That's all, not a thing to hold the submission up over but wanted to make sure that was clear so the sheet looks polished. I'll approve for the next person to review, but please update it 
Ohhh, ok. Those tools are somewhat new to me, so thanks for the explanation! Think I got it.
Looks pretty solid! There's just a few (recurring) things I noticed:
-Anytime you have this figure:
I hear it as this instead:

I'm DEFINITELY hearing a C...but after listening to it again, I actually do hear the D and Eb, as well. I did both.
-I hear the marimba figure that plays in m15-16 (and else where) an octave lower. It doesn't matter too much either way, but having it an octave lower does allow you to keep the "high" C from the strings.
Yeah, I purposely transferred the marimba part up an octave. I think I'll leave it as is.
-From 37 on, it may be a nice effect to add a long C an octave below the L.H. every 2 or 4 bars, to add a bit of tension and to imitate the low strings.
Good suggestion. Updated.
-m50 and 54: I hear a C on beat 2 instead of a D.
I'm for sure hearing a D. Any second opinions?