im not sure if it asks for a "handshake
Handshaking involves one end of the serial port sending some throwaway data to the other, signaling that the sender is ready to receive data. The Arduino sketch that you linked to never writes anything to the serial port, so there is no handshaking going on.
If you comment out the 1st two lines and the last line in setup(), and the name of the song being played is printed, then when you are able to uncomment those lines, because you actually have an Arduino connected, the song title will be sent to the Arduino.
Notice though, that when that song ends, and another song begins, the title being displayed will not refresh.
This is because the setup() function in a Processing sketch is like the setup() function in an Arduino sketch, in that both only run once.
If you want something to happen more than once, in the Processing sketch, like detecting that the song that is being played has changed, you need to put that code in the draw() function.
It would be useful to keep track of what has been sent to the Arduino, so that you can send new data only when a change occurs, rather than every pass through the draw() method.
The println function actually sends two characters, in addition to the specified series of characters - a carriage return and a line feed. Not that it makes any difference, since the characters that the sketch doesn't recognize, like carriage return and line feed, are ignored. It appears that you don't need to use println or add the \n to the serial stream.