Yeah, I would avoid anything from RENT, unless absolutely necessary.
Songs from Tommy, BatBoy, and Children of Eden are all excellent ideas.
As for Joseph, nothing really in that score comes even close to the range that Jesus or Judas has to sing, so if I were going for those roles, I would stay away.
Also, singing something from the score is not a bad idea either. I used to be of the school of thought that you couldn't sing anything from the show, but on occasion, I have, and gotten callbacks. It can't hurt. Especially if you have one of the songs already in your repetoire.
"Pity the Child" from Chess is also an excellent idea.....especially if you are going Judas, and you can sing that song in your sleep. DON'T use it unless you have practiced it.
"Someone tell the story...Someone sing the song...."