Well all of that depends on what version you are auditioning for ('62 or '87) and what kind of production it will be.. High school, Community theatre or Professional.
Here is the script for the '87 version
And also, as I said, depending on what kind of theatre.. Unless its pro, I doubt you will need to be a very strong singer.
We did the show at school last year, and although it was just high school, we had an amazing Moony. Couldn't sing to save his life, but so many audience members said "Be like a bluebird" was their favourite song.
So break a leg at your audition!