I think a plain blue dot indicates a new thread since you last visited. A number in a blue circle means it’s a thread you have previously read, and the number is the count of new messages since you last read it.
The dots and circles don’t automatically vanish when you read the thread, but if you reload the page after that, they will not show up.
Like this?
That’s not an indent, but entering a few times. That is the HTML code for a non-breaking space. Which can be a way to annoy people who are strident about using a single space between sentences. 
It appears that if you wrap text in HTML unordered list tags (<UL>…</UL>), that will indent a paragraph. There won’t be any bullets if you don’t also have a list-item (<LI>) tag in it.
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Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
Other mechanisms I tried (e.g. embedding CSS code in HTML object tags) doesn’t work - DIscourse filters them out. And its BBCode module doesn’t support BBCode’s paragraph-alignment keywords.