It's one of those questions where several solutions are all probably good enough, and the best one depends specifically on your content.
Definition lists can be quite awesome, and while they can't have list-styles on them, you can have ul's inside the dd's so you could do
list of thingies with bullets
<dt>another header thing</dt>
However dt's only show a semantic relationship between what's in them and all that's in the dd, in the way that a term is related to its definition. Looking at your document outline, these will not come up like heading tags will (you can also put heading tags inside dt's if that makes more sense):
but then you start really straying from bare minimum and you end up asking yourself what the dl tags are doing in there anyway... since a heading tag "heads" the content beneath it until either the next header OR the containing context ends.