Nice clean HTML5 code, thanks.
Just a small bug:
When first saving the settings neither 'Image Caption' nor 'Script and Style' settings were checked. I set my defaults for linking etc and saved, but on refresh the Image Caption and Script and Settings checkboxes had become ticked by themselves.
And some feedback:
What would be really useful would be the option to apply the link to the caption as well as the image. I often need to float captions over clickable images, or at least have them clickable underneath the image, so this option would be the cherry on the top of a great plugin for me.