Hi Sara,
You are so right about needing to provide all of the course requirements at the beginning. If an instructor does not the course is going to be rocky at best when changes are made and need requirements added.
If the syllabus lays out clearly the course expectations, requirements and polices then both the instructor and the students know how to operate within the course. If changes are needed they can be made with clear understanding because the students know the parameters of the course and the reasons for the changes so they don't get upset when the changes… >>>