This is actually really tricky and has been kind of confusing since I got here. I wasn't sure what was happening to the comments when I clicked the wheel. Does this make the post "more shared"? Does it put this comment at the top, but only for people that follow me? Or is just like a reddit upvote? I understand how the post voting works, that's pretty simple. It's like reddit, and people can subscribe to things you share. That understanding came pretty quick while I was on here. Up until now, I've been hesitant to "share" comments, seeing as they aren't all something I want to "share". But if they just move the topic up and say "this is a good comment" then I'd be more likely to "share" it.
Did you ever figure out what does happen to a comment when you click the wheel? I haven't been able to figure that out myself.
Yes. Clicking the wheel essentially says "I like this and want others to see it." So when you click it for a submission/link, it "curates" that into a feed for the people following you. For comments, it makes that particular comment show up higher in the list. Similar to an up-vote on reddit.