I'm trying to put tongue and groove on a ceiling in our dining room. The joists that go all the way across are 20 inches apart. I'm not sure whats going on with this, but I believe it has something to do with the roof, as there are many angles in this area of the home. I'm not 100% certain of the diagonal studs, but I did cut away some sheet rock and confirm it is that way on one side. Can anything be done here without ripping off the drywall? NOTE: on the left side, the red line is heavier due to an available stud for anchoring .. there is no stud present on the right side for anchoring. Please excuse the drawing, it isn't exactly to scale, but at least you can see my situation.

I'm preparing to start the dry walling phase of my basement finishing, and a question on best steps in placing the drywall around a few soffits. I'll be doing the ceiling first, and then the walls. But when it comes to the soffits, should I do the 'bottom' of them first before the sides? Or do the sides first and then bottom last?