I get laryngitis about twice a year. Is that abnormal? I work in a profession where I need my voice. How do you cure this?

Laryngitis. Larynigitis (a viral cause of acute hoarseness) is a pretty common infection. Everyone will get it, and usually more than once. For most adults they get it every few years or so. If you are in a profession where you use your voice a lot, then these episodes of hoarseness twice a year are probably not viral laryngitis, but are probably episodes of voice decompensation related to your work.
One at a time. 1) depends on how much you use, or overuse, your voice. 2) if you need your voice you must do everything necessary to protect it. Please don't smoke, get plenty of rest, and see an ENT surgeon as needed - you don't necessarily need surgery but you probably need an evaluation including a scope to take a look at your vocal cords.