1. Can changes on a generated 2d section view be remembered in the model?
2. Can I add an object like a picture frame on a wall in plan, and have it show up when I generate an elevation using a call out tool? I know how to turn a pline into a wall modifier, but that's not what I want.
1. Changes made to a generated 2D section or elevation have no affect on the model file(s) used to generate the section/elevation. Depending upon the nature of the change, it is possible to reapply previous edits to a regenerated section/elevation, even if the geometry in the model has moved.
2. You can do what you ask, provided that you model the picture frame in a way that generates graphics in an elevation view. A simple 2D polyline drawn in a plan view to represent the top view of the picture frame will not work. But if you build a Multi-View Block with a properly oriented elevation block, that should show up an elevation view and also in a generated elevation.