Learning openings

How much you should study openings depends on how much free time you have. I would recommend learning the ideas behind basic openings (Italian, Queen's Gambit, Caro-Kann) and then move on to more complicated openings (Catalan, English, etc.) You don't really need to worry about theory until 1800-ish elo.
Chess.com also has a Study Plan Directory which is really helpful:
Study Plan Directory - Chess.com