Getting a feed of actionable items

Almost none of the existing feeds provide any value to me. The "most recent" feed is ok because it shows which posts have had recent activity. But I haven't figured out how to limit that to only those "categories"/"forums"/"hubs" that I'm interested in, omitting the ones I'm not interested in. 

Is there a way to make the "most recent" the default, at least for me?

Is there a way to "follow" a category besides subscribing to email notifications? Once I've followed a category, is there a way to get a feed of just those items? 

Once I get a feed of just those items, is there a way to highlight which ones are unread by me? I do see the "1 unread" on some posts, but it's the same color as everything else and doesn't stick out very much. Optimum scenario would be the ability to filter the feed to show only unread threads and threads with unread replies.