I think I am still confused about Firmata.
I'm familiar with parsing serial bytes received by the Arduino but I was hoping to avoid that. For instance, instead of me sending the bytes, then having Arduino determine what those bytes mean, I could have just wrote something like arduino.analogWrite( Rpin, PWMvalue ) for each color and the Firmata would have interpreted that behind the scenes and accomplished the same result.
That's what Firmata does. What are you confused about?