I would add another concern, which is implied in your list, about the metric or the basic units being measured - e.g., what does the number of "interactions" tell us about the "quality or value" of a discussion?
How do we compare data from a Moodle course that is set up as an instructor's resource dump versus one that emphasizes learner participation in discussion forums, wikis, and in discovering and posting relevant resources for the learning community of that course?