Thank you!
Unfortunately, these things are not covered in FAQ's
But I figured the first part: to start subscribing to discussion threads and keeping track of replies, go to User CP, click on Email Options, find a box called "Default Thread Subscription Mode" and set it from No notifications to any frequency option and save changes. This will automatically start subscribing you to the threads you posted in.
But I still don't know how to make a quick list of threads you'd like to watch without posting in them.
And I have no Mood icon whatsoever under my avatar so far or is it just my browser not displaying it? Everyone else seems to have theirs. Someone mentioned it's a bug that will get fixed at the end of the month after updates