LiveJournal can always use more volunteers, and helping out in Support is a great way to learn more about how LiveJournal works. However, it is a time-consuming task that requires patience and professionalism. Don't expect to just jump in answering questions and get a bunch of points. For many volunteers it will take weeks to earn their first support point.
You can indicate your mood in any of your journal entries. The mood you enter will normally be displayed with your entry, and if it's one of the server-supported moods, a matching picture (a mood icon) will usually appear too.