Regarding playing things well under pressure...
Record yourself! Constantly! Listen to your playing and be objective. Play for other people, especially for people who don't play the bass. I've been getting amazing advice from a flute player recently.Cellists and violin players are great too. Remember that audition committees are made up of more than just bassists.
Also slightly more practical- Make sure you can play things faster than you need to.
+1 for practicing with the amount of hair you'll need at tempo. For fast articulate passages this will involve a ridiculously small amount of hair at slow tempos. Mr. Muroki recently had some commentary on this, as well as using a light touch on a thread about 35.
Good Advice!