Okay. So I've been playing chess on and off for a few years -- I consider myself a "casual player." I know certain strategies and to try to control the center of the board and things like that. I've never really learned openings, however. How important is it to know specific openings? Are they so important that they make or break the game and separate the masters from the novices, or can one get by without memorizing patterns, simply by being cautious and watching what the opponent is doing?

Knowing openings means you don't have to spend lots of time trying to understand your opponents moves, since you've already done your homework ahead of time. It also means you understand the general plans for both white and black, the themes, and any traps. Not knowing openings will generally mean that you get an inferior position to work with in the middle game, or you have to spend a lot of your clock time (assuming its a tournament) figuring out in a couple hours what people have spent days/weeks/months studying and writing books on. However, in my opinion, it's best to just understand the general theory of most openings, and not try to memorize too much. Memorization can play tricks on you in a game, and leave you not really understanding why it is you're making those moves.

No, but it helps to understand your "repetoire".  If you play chess you have one.  It's the moves you like to play.

Go read some about them.  Go see how the masters deal with it.  It will improve your game.

But no, if you want to improve your game most as a casual player, practice tactics.  It is "losing" chess rather than being beat, that is the most common problem for the casual player.   

The opening chess is very important becouse all the game is about since the begin until the end.