Here are a few tips for working with multiple content types within a box.
Both Standard and Tabbed box types will have icons in edit mode showing you where one content element ends and where you can add another element.
After you have created your content blocks, you can reorder them.
Tip: If you are using h3 or h4 tags to separate content (good for you!) , you may have to create a lot of Rich Text / HTML blocks to hold those headers, then reorder them.