Implemention of fancybox to modify the image display/gallery on our website and make mobile friendly

We would like implement fancybox to modify the image display/gallery on our website to fix a problem and make mobile friendly. Our website has an admin panel which we add/remove/modify listings, adding and sorting photos etc. Since we upgraded our server to a new php version the website stopped automatically cropping photos to put necessary places in the website like display photos/thumbnails/full versions etc. We would like to fix this problem and make it automatically create necessary cropped/resized files and also we would like to change the way of displaying images on our website and make it mobile friendly to show perfectly also on mobile devices. In summary; The way of uploading photos will be changed. We are now selecting files one by one at the admin panel when uploading. We should be able to select all or multiple selection or drop all images to be uploaded to a specific vessel. System will resize/crop all images to its necessary sizes automatically and place them wherever it will be shown. On all mobile devices including Android and iOS gallery and the way of showing photos in vessel galleries will be changed and become mobile friendly. It will automatically fit to vertical and horizontal use of screens in full page and there will be an easy way to show thumbnails of all photos to select to check the one they need.