How to get a list of all songs in iTunes?
This is actually insanely simple:

Open iTunes and go into your music library. Click on a song to ensure focus is inside the song list, press ⌘a to select all your songs, then press ⌘c to copy them.

Open the text editor of your choice, anything should do, then ⌘v paste your songs!

Ét Voíla, all your songs listed in plain text.