Newbie question about how to get set up
 

I'm new to GTD and new to OF, and confused about how to set up OF for my work responsibilities. Specifically, I have about 100 matters that I oversee/handle, and am responsible for making sure that they move along, with action taken and a detail note recorded at least every 90 days in each matter. How would you recommend I set this up in OF?

In general, I would guess that you are going to want to add a project for each matter that you oversee. You can put an action in each project to make a note of progress. If you open the inspector window, you can set it to repeat, either "Repeat Every" if every 90 day period should have an update in it, or "Due Again" if there should never be 90 days between notes. It is probably a good idea to set a start date on that repeating action as well so it does not show up as being ready to be done again as soon as you check one off.

I personally think that OF is not the best choice for keeping track of what actions you have taken, as opposed to what actions you have to do. If you open up the view bar and set the availability filter to "Completed", you will see the actions you checked off, which may be a useful reminder, but I think it is easier to keep track of the work you have done in another application.

Lucas, are you suggesting that I add each of the 100 matters as 100 projects, and then add at least 2 (parrallel) Next Actions for each matter: (1) the next action to take to move each matter along (marked due again in whatever time frame is appropriate for the task, at most 90 days away) and (2) writing my note every 90 days or less stating the status and what I've done (marked due again in 90 days)? Have I understood you correctly?

Yes, that is my recommendation from what you said in the original post.