So this is taken me more time than expected (and some other work came along). Here I first upload an idea of what my original document, before using asciidoc, looked like.
At the current situation in asciidoc, I have the document as one long html page, with the TOC on the left side.
The yellow block from the old situation has become a 'NOTE' admonition block. The red block became a custom admonition block.
I placed the top-right 'icons' horizontal in an example block. It's different but suits my needs enough.
I placed the A-U table at the bottom right in a sidebar block.
Both blocks have [.right,width=50%] attributes.
My problem at the moment is that the admonition blocks cannot wrap next to the A-U table. Instead I get a big white gap.
Another issue is how to implement the little paragraphs of table and figure captions. Any suggestions are welcomed.
I'll try to give some more (visible) insight on what I have done in asciidoc tomorrow.