I guess the problem is the code in processing
Yes, you are trying to call methods that do not exist.
is it in the attached file cc.arduino.* or the file processing.serial.* ?
No. It is in your code.
does this command work with the arduino library
Does which command work with which Arduino library? If "the arduino library" is the one in Processing, you need to check the documentation (or examples) for the methods that the arduino object implements (and exposes).
I am new with serial ports and don't really know where to start debugging this issue.
It isn't a serial port issue. You are trying to call methods on the Arduino object that do not exist. The Arduino object you are creating is not a serial object. It is an implementation of the Firmata protocol for Processing.