I wish there were more space on an octavo. If there were, this is what I'd include:
Thank you for purchasing this arrangement
It might be your inclination to sing every note exactly as written, but I strongly urge you not to do that.
An arrangement is nothing more than a road map to get from point A to point B: in this case, help you communicate with your audience.
Like a speech, you want to know what you're saying, and craft the words to fit your own voice and your own interpretation of the message.
What should you change?
First of all, I recommend you study the original song, and find your own meaning within it. This will give you a direction and purpose to all of the musical decisions you'll make regarding dynamics, phrasing, etc.
You need to be saying something when you sing, and if you don't have an overarching mood or message, your performance will likely not make much of an impact on any audience.
Secondly, you want to make sure the technical aspects of the music are appropriate to your group. Like a custom-tailored suit, you should tuck and hem where needed: if a bass note is too low, a phrase too long without a breath, a dynamic too stark.
A published arrangement is like an off-the-rack piece of clothing, and whereas it might fit you very well, there is usually something that can be altered.
Please know that if I were personally in your rehearsal with you working on my own arrangement, I'd undoubtedly make changes. I might even insult the arranger's stupid choices. It has happened before. More than once.
Many arrangers are very precious about every note, and upset when a piece of music does not sound as they have anticipated in their head. I humbly submit that you should not care at all what the arranger thinks. Moreover, you should not be aspiring to the tastes and Platonic ideals of some music theory nerd halfway around the globe.
You should make music that resonates with you and your fellow singers, and most importantly with your audience.
These statements might anger my fellow arrangers, but I can take the heat. They should understand that the changes you make will improve upon your performance and make them look good.
If you have any questions, you're welcome to email me. I also love feedback, as it helps me become a better arranger.
P.S. There is undoubtedly an incorrect note somewhere in this chart. Possibly two. It's in there to keep you on your toes, and give you something to search for while the basses are going over their part (again). You might think that it's an editing error, the result of imperfection or laziness, but I assure you that is quite impossible.