I figured out the beauty of the "2d geometry" tab. It lets one arbitrarily add geometry to the model. That enabled me to solve both of my problems.
For the first, I just created a line segment that connected the green line between the arrows. I turned snapping on to snap to the intersections of the model's geometry. Easy.
For the second, a simple rectangle became the pocket. Easy again.
If anyone has better suggestions, I'm all ears, but this seems to be a powerful tool. I learned on an old 2D version of MasterCAM, where I only used the CAM to draw my geometry. This takes me back to that.