What is the effect of PCB trace length to a capacitors frequency response?
My assumption is the manufacturer obtained the frequency response curve with zero or minimal trace lengths. How does the resonant
  frequency shift because of the traces?


For this particular question, I see that there is not perfect or universal method for the measurement of ESL.ESL numbers are generally obtained by making a measurement of the inductance of a capacitor in a given circuit and comparing that value to the inductance of the same circuit with the capacitor shorted. This method is seriously flawed, since the inductance of a current loop is not the sum of its parts. As a result, ESL numbers published in datasheets are strongly dependent on the method and apparatus used to obtain them. Furthermore, there is virtually no correlation between the ESL numbers published in a datasheet and the connection inductance that determines the high frequency impedance of the capacitors in real applications.

Further info:
http://learnemc.com/qotw-180604

The other part of the question is already answered.