In response to 1.
Its a hack to do it in document-links imo, document-links require at least one DocumentCategory and none of the categories fit pictures.
Saying that, its also the only option where you can validly hack it into IATI a bit without using namespaces (which I’ll never use). We implemented it on aiddata.rvo.nl since it does enrich the context of the project, especially for their type of projects.
https://aiddata.rvo.nl/projects/NL-KVK-27378529-PSIP13OT31/?tab=summary
https://aiddata.rvo.nl/projects/NL-KVK-27378529-TGOS140001/?tab=summary
(there’s more on the media tabs).
We used document category A12 (= Activity web page… well its at least shown on the web page!). Labelling + captioning would have to be merged in the title, we did not use it.