After looking at Chapter 8, its becoming obvious that learning Westergaardian theory to an extent that it would be actually useful to me is going to take a lot of time and analyses (and I don't know if I will get around to that any time soon).

Regarding harmony, this document may be of interest to you - its written by a Schenkerian who is familiar with Westergaard:

http://www.artsci.wustl.edu/~rsnarren/texts/HarmonyText.pdf