/wp-contents/plugins/
directory.Q.: I see a dropdown for users but it does not work A.: the dropdown is for Administrators only. You must set each Admin one by one if you want each admin to have access to the visual editor. Yes, please contribute and fork from Github or ask on WordPress plugin page for support. This is Open Source.
WordPress removed a lot of components from the latest versions to make way for more room on the page. Older versions of MVEd would open up these hidden elements to use, which will show just below the two active menu bars of the Visual Editor. Font Family, Font Sizes, Formats (dropdown), Background Color (Hightlighter), New Document Cut, Copy, Special Characters, Horizontal Line There are a few more that are commented out in the mved-modify-media-buttons file. After version 0.2.0 we discontinued these to streamline the plugin.