How would I go about adding the functionality of subscribing to notifications or alerts via RSS feeds for certain pages/documents or images?
You can create custom feeds using the views. This can contain any fields as you want. And use all the filters, relationships and contextual filters to get the exact feed that you are looking for. The you can place feed link where ever you want it to be seen. This would be done using blocks or may be simply by adding it to the page.