Are you holding your breath while your head is in the water? This may be causing the hypervent. You should slowly expell your breath underwater to match whatever stroke cycle you're working with, then inhale naturally without gasping for air on your breath stroke.

Like everything else, the more you practice the better you get.

Adventure Bear has a good link on the Feeling Bloated thread.

You're breathing way too much. As long as the rest of your form is at least decent, there's no reason to breath more than every 3rd stroke. Generally during long swims I'll breath every three (four if it's too sunny on one side! ;)) And that's a maximum amount of breathing. When I was still sprinting, the only 50s where I was able to go under 22sec were the ones that I only breathed once during the whole race. Breathing less often (especially to opposite sides) will help maintain your line in the water as well. Breathing often and on the same side will most likely cause you to "snake" through the water, which is going to be less efficient (and make you hyperventilate, too!). Just make sure to breath enough to get sufficient oxygen to your muscles, no more, no less.