The caption could be done as a paragraph style where you apply numbering to the paragraph style. Then, you could define the text of the captions as paper color, whereas the number could have a character style that defines the number as the ink color black, for example.
For the list at the end, generate a Table of Contents (there can be more than one ToC in a document) that will act as a end index to the pictures. The gathered paragraph styles will be styled with a new paragraph style named maybe index_to_images and its color can be defined as, maybe, the color black.
Thanks, A few extra tricks were required, but it really helped! Hope I remember the workflow tomorrow.
The Table of Contents has worked fine with a little tweaking every now and then. However, I have just run into a weird problem:
I have eight images on the same page with captions below them. These captions link to the ToC and they show up just fine, only they are in the wrong order. I have cut and re-pasted them in the order I want them and the caption numbering changes automatically to the correct figure. But the ToC still has the sequence mixed up.
So: The order of the captions in the document is correct, not only positioned correctly in the layout but also placed on the page in the correct order. The ToC doesn't care and scrambles the sequence anyway.
What to do?
TOC picks up text starting in the upper left corner, then moves down before moving right.