You can't do Serial.print() in an ISR. Get over it.
That renders most of your Arduino sketch rather useless. What you need to do is periodically, determine how many pulses have occurred, and divide that number by the time over which they arrived, and send that, as speed, to the Processing application.
String pulses_raw = myPort.readStringUntil('\n'); //read until the new line, like print ln
You should not be doing serial input in draw. Add the serialEvent() callback, and do your serial input in serialEvent().
I'm not sure why you aren't sending something like "speed=someValue" and "lightLevel=someSensorReading" and "thisOtherValue=thatValue" to Processing, so you have a clue what the string you get represents.