Use File Chooser to select a file. Then on use FileChooser On Changed event do Sprite Load image from URL, where URL= FileChooser.FileURLAt(0)
Then on Sprite Image Loaded event you can resize it if needed. Note, that if you want to load multiple images, you need multiple sprite objects, or one object with multiple frames. The image is loaded into the current frame.
I'm not sure about cropping. You can "crop" part of the image with Canvas or Paster addon. You can also load image directly into Canvas/Paster skipping the sprite.