If you want to auto-rotate JPGs according to they EXIF information (if properly saved), check the first option.
If you check Load as grayscale, ALL loaded JPGs are showed as black/white. Please remember if you activate this option!
The second check-box handles the transparency of non-animated GIFs. Check it, if you want to Show transparency in non-animated GIFs too. Please remember if you activate this option! If your main window color (default: black) equals the GIF transparent color, in some cases, you will see just an empty (black) image. Either deactivate this option or use another window color in Properties->Viewing.