When I use dash and when I use star
Org-mode has two (probably more) ways to make nested lists. Either with dashes or with stars. How they behave are very different. The dashes are just a list, while the stars are actually more of an outline and they are rendered into headings if you export to HTML.
What I use an when depends on what I want. Most of the time I use dahses for lists. And here in org-roam is usually never make documents that are deep enough to need a lot of outlines, but sometimes I do. But I only use stars for headings.