Is there a way integrate redactor with your assets fields? Does anyone know if there is a way to extend redactor to render a template, for example, when inserting an image so that it could also display custom asset fields (i.e. caption, photo credit, etc.) in a small html block? I have no idea how difficult or easy it is write redactor plugins.
A better way to tackle something like this would be to use a matrix instead of just a rich text area.

With a matrix you can have an image block and then in your template you can pull any info you want from the images custom fields.

We normally have at least three block types with a normal matrix, text, image, and gallery.

Text is just a refactor text block.  Image is an image with a "position" field to control alignment (float left/right/center) the a gallery block which lets you select a series of images which display in a slideshow