How to handle the stress? Not sure... but my way of dealing with it is: "keep things in perspective". I am not saying I take my job lightly. In fact, I take it very seriously and I hate to get a SQL notifications telling me one of my jobs has failed but...

Keep in mind what is important in life is absolutely vital to staying sane: pictures of the kids on my desk, running between 50 to 80 miles a week, talking to my parents and surrounding myself with true friends has helped me tremendously to deal with stressful work.

As far as solving issues in a calm and composed manner, listening carefully to issues when they come up, getting advice from very experienced SQL developers and DBA from SQL Server Central, reading very free PDF from Red Gate and Phil Factors' blog, and mentor less experiences developers are keys to keeping a serene piece of mind.

That's my take on it. Eager to read more answers.