Can the principles of Vastu be applied to entire townships? There is little mention of this aspect in your book.

Town planning has not been covered in the book because most people want to know about Vastu in relation to their personal dwellings/offices. To answer the question; yes, as far as the climatic aspects of Vastu are concerned, they can naturally be applied to townships at both, the individual as well as at the overall levels. However, that is no substitute to good town planning. Vastu can, at most, play a supporting role in such a situation.