I almost missed my deadline because I also had a lot to explain in my choices.txt and I wanted to do it thoroughly because I'm not a native English speaker and wanted to make sure the accessor really got my points without possible wrong interpretation. I just add everything I could think of and ended up with a decent file of 5-600 lines (of max. 80 characters).
It's your call to decide what is important and what is not. No one can tell you what is important and what is not about your assignment, but it should be obvious that locking and networking are 2 big issues and should be explained very carefully
Here you can find my table of contents of my choices.txt, maybe it can give you a little bit of inspiration.