Try this site Emily it may help?;-

http://monologueblogger.wordpress.com/

If you know the part your after try & pick something generic with it or in the same vein.
Similar with the song, from my point of view I look for singer who can act, rather than a singer who is a log of wood or a stale bottle of milk  with a fabulous voice.
Sell the song by using your voice to tell the story.
There is various tricks including speak/sing where by you emphasise the meaning of the line with sing speech & finish each by singing the end phrase of the line.
This probably doesn’t make much sense, I’m sure the singers amongst us will give a better explanation. Grab any cast recording of a musical & listen to the voice in a solo, beyond the music.
Remember to use your voice from the diaphragm, not from byour throat, practice by placing your hands on your stomach & feeling the air movement while singing.
Also do it front of a mirror & remember your not in a choir, your the character.
Tio Tio Tio Chookas Emily!

Bewdy Emmy!
 Before I’m shot down by others. on the board, flame out & prang up! - I’ll test my techie wings further?
Think about your audition party piece & think out an imaginary back ground for the character, giving it a life of it’s own & how you perceive the characters life got them there, prior to their entrance on stage. This works with the ‘Logues & the song equally.
One trick I suggest to most warm props, is to think of a song or piece of music that best describes the characters life or situation.
For example a King or Queen’s entrance use a regal piece of music such as ‘Pomp & circumstance’ in your head & you will become a Queen in body language & attitude. Or if your playing a cometic Scotsman [women] sing a song like ‘Donald where’s ya trousers’ in your head & it will help you get in character & accent before you step on the boards.
Practice in front of a full length or cheval mirror at home.
Do a dress up with improvised gear from your wardrobe & a bit of character make, that will give you a mask t& help you step outside of yourself! Even if you ‘arf inch you mums for the exercise.
keep practicing your pieces, keep exploring the characters & even re-inventing in your head the possible back life of the character & their aspirations. Even until you send everyone in the house - up the wall!