The device has a display with three full subpixels per pixel, resulting in a sharp and crisp picture. Pixels in some displays (like AMOLED) share one subpixel to preserve space. This can result in a less crisp, slightly blurred image.
If an app has sharing capabilities and the developers have indicated it, the app will automatically appear in your list of sharing options. Some OS’s limit direct sharing options to a select few apps, which means you have to open apps separately in order to upload the files you want to share.