While lavishly illustrated exhibition catalogs and glossy art magazines are much appreciated and easier to read, these publications tend to ignore the religious underpinnings of Asian art.
Instead of providing a broad historical view of the statue and its significance as a “living icon,” they tend to emphasize a piecemeal "bite-size" approach involving aesthetics, dating and provenance, technique, material, genre, and style.
First and foremost, this project is a labor of love.
As for online resources, the Japanese Architecture and Art Net Users System (JAANUS) is by far the best digital dictionary devoted to Japanese art.
A third copious source of information comes from temples, practitioners, spiritualists, and independent web bloggers.