Is there a way to adjust the size of the cursor while editing a document, or to make it stop blinking?
You can make it stop blinking via the Text Editing Preferences. You can make it wider, there, too. There’s no control over the height, though, as that is controlled by the underlying OS X text system (i.e. to the best of my knowledge there’s no way I can change the annoying way the cursor takes up too much height when there is line spacing).
All the best,
Keith