Darkens the current page and displays an image (like Lightbox, Thickbox, etc.), but is a lot smaller (10KB) and faster.
Since Shutter Reloaded does not use any js libraries, it does not interfere with them.
Then none of your links will be changed and will work as usual.
No, Shutter Reloaded looks only for links pointing to an image (with thumbnails or not), and will not change any other link, even if the link has the same CSS class used for activation.