When I try to add a new article from the login module (add new item) I cant view the entire popup window the topo of the save and cancel button is cutoff and the bottom of the editor is cutoff in firefox

Thats happen because the modal iframe its set to 990x650 and probably your screen resolution doesnt match this size. you can change handler size for minor values.

How do you change the size of the window??? Where do you go to do this

Try userblock.php - search for iframe