The DIV properties box should be improved. You should be able to set the style, ID, absolute/relative position, the visibility, the z-index, etc...
The image dialog should have an option for 'set the name to the filename minus extension'. This should automatically be set if certain scripts are being used.
There should be an 'event handlers' button in the edit link dialog. Ideally, this is where the calls to the scripts can be created. This is where the whole thing gets complicated. Many of the scripts require different parameters. I'm not sure of the best way to handle this. Maybe the dialog could display the tag as it actually is written.... like so: switchimg ('______', '________'); The fields could be labeled accordingly and have pulldown menus from which to choose options. In this particular script the first field is for the 'name' of the image to be changed. The second field is for the filename of the image to replace it. (Could be a 'browse' button?)
Other options would be completely invisible, like adding the 'detect.js' script to the header, or adding the 'preload.js' script.