"You can put images into Scrivener and it will export them"
How does it do that? I drag pictures into Scrivener and it does not export them into Word files. I drag them into the Inspector and it does not export them, either. There seems to be no settings in Preferences to force Scrivener to export pictures. Even Compile Draft does not export a single image.
In fact, as observed by the first poster, Scrivener seems to be terrific for text based writing. For any technical writing that includes many footnotes and graphics/images/drawings/illustrations, I cannot recommend Scrivener at all. What a pity!
I use Scrivener for writing which includes footnotes, diagrams, etc. The problem is that Apple's basic RTF doesn't handle them, therefore most of the word processors based on the Apple text engine, e.g. TextEdit and Bean to my knowledge, and also Pages — though that seems not to be based on the same text engine — and others ignore the notes and images. You can export to RTFD and Bean and TextEdit will show the images, but not the notes, but RTFD is very limited in its use. On the other hand Nisus Writer Express handles both images and notes, and you have the choice of exporting annotations as margin comments or inline annotations. Neo/OpenOffice both display the notes and annotations using RTF, and, I imagine the images, but I haven't needed to test that.
I cannot really comment on Mellel as I don't use it, though those in the humanities who use Scrivener and who need long footnotes, say Mellel is better from that point of view, and Mellel seems to read Scrivener exports without problem.
As for Microsoft Word, I am a Microsoft-free zone so I can't comment.
That said, for images, I tend to do as a previous poster suggested, and just put a place-holder in Scrivener, and then place the actual image once I've exported to NWP, as I can use LinkBack then should I need to edit the diagram at all. If I need to see the diagram or image while writing, I import it into the research folder, and open it in the other split.
The same goes for call-outs ... I write the text that is going to go in the call-out box and mark it, by putting a simple annotation before and after the text, e.g. "call-out" before and "/call-out" at the end, and then move the text into a text-box once I'm working in InDesign, Pages, or similar which handles text-boxes ... NWP doesn't yet. Scrivener is not a page-layout programme or word-processor ... such things as call-outs and graphic placement are best left to applications designed for that.
EDIT: Jebni, being less verbose than me, posted his/her answer before me, so apologies for a certain amount of duplication of information. Again, as I understand it, the Apple docx exporter is deficient.