You state : It would be nice if assignment due dates could be set as relative to the course start date ...
My school is on version 1.9.something
I have noticed that assignments have due dates but Quizzes and Exams do not have due dates only open and close dates. Are Due Dates for quizzes and exams something that will be added to Moodle 2? It would be nice to have them!
For quizzes that have no close dates (highest grade counts) but have to have a specific grade by a specific date, that would be wonderful! My students take the quizzes over and over for repetitive learning.
I leave tests online forever and take off points for late tests, but there is no Due Date setting which let's the students know the date they need to have it completed. I simply leave an announcement and post a schedule so they know, but a due date would be much better.