I saw no problems using the visual editor. Can you try in another browser and see if things work. May be you have a browser extension that is blocking the editor function?
I was able to add images too. Only issue I see on your site is that the images which were in media library have been deleted somehow manually via FTP or file manager provided by the hosting provider. You can always restore them by doing a bulk delete on the existing images in the media library and reimporting the same or you can manually add the images that you need. Most of the demo images are not to be used on your site anyway.