Mike, welcome to the club. The information you seek does not exist. There are general guidelines, but as for the specifics it is trial and error.
I teach health informatics (www.shis.uth.tmc.edu). You can poke around our moodle installation (moodle.shis.uth.tmc.edu). Login as guest, look around, let me know and I can open a course to you. Foundations I is the one I have spent the most time designing, the summer semester should be open.
In general, the more time students spend on task, and the more they interact with the material and with each other, the better.
First you have to decide what you want the outcomes to be. Robert Mager gives you guidance in writing objectives, that can be a painful but indispensible exercise. Look at Bloom's taxonomy as well to get an idea of how well you want students to do whatever you have them do. Then you design "stuff" to try to get students there. A variety of different ways work best, google Gardner's multiple intelligences.
Last, assess your students. That can be accomplished using a variety of "stuff". It depends on your objectives and how much time you want to spend assessing (think grading essays vs autograding multiple choice exams).
In general, I do objectives and assessment first, then put the stuff in between. Be prepared to iterate, be prepared for surprises (they STILL don't get it, after providing a lecture, readings, exercises, chat, a video where someone works through the problem)
I am also doing research on what works, which I am happy to share as we get results. We have looked briefly at chat and did not find participation in chat to influence grades (caveat: small group, short time).
If you want to talk to me directly, my email is Irmgard.Willcockson@uth.tmc.edu.
Best wishes for your journey. Irmi