Both page index and page name might be tricky. If you would link the shape to get data from page by using the index. The link would be broken when you rearrange the order of pages. If you link it to the page's name it would lose its link when changing names.
All i can think of is catching changes in page order and names, might be allot of code for a small problem...
You would have to catch, Page added, Page deleted, Page changed, Document changed (for page order?)...

Tricky...
I'll think about this one tomorrow, might get some brilliant ideas during my days off.
- Lars-Erik