It went okay. I took Minstrel Boy's advice (since I have absolute trust in his judgement on music), and they really enjoyed the song. I was a little shaky from nerves when I sang it, which I hope they will spot me.
We also did some exercises. I could tell they were impressed with how low I can sing (B below the C below middle C - impressed eyebrows were raised, I still have resonance that low, provided I'm not too warmed up). I sang in close harmony with one of the members; I thought it sounded good, I listened to her and adjusted to her dynamics, and I had no problem keeping my part accurate.
They said they will have a callback next Monday, so I have another round ahead of me. Thanks everyone for your input on which song to sing.