NOTATIO

For the second situation, I would either use doubled noteheads, or just have one voice disappear. Since the staff is labeled appropriately, it can be understood that when they are in unison where single notes appear when mixed with harmony. You could use double stems, but I think it would be ugly an...

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I would go with single note, since the tied note is going to prompt questions.

Just say no to C scores!

While it's generally proper in a text, in the music I think it would be distracting.

If you print out a copy of the text (like as a foreword) you can italicize the foreign words there.

I definitely used to be more cavalier about order/placement.

I like this greatly.

I have found myself using "p sub." etc., more often as of late. For me, making sure the dynamic is right under the correct note is paramount.

I like 1, 4, and strangely, 7.

Thanks, everyone!