The Cabasilas book is quite good, and you should definitely read it. There area few of the so-called "mystical" books on the Liturgy that you could read (from St. Germanos, or St. Dionysios, etc.), which take a very figurative approach and speak more of connections with Historical and Spiritual events rather than interpreting the prayers and providing practical relevance info.
I've got a new one that I haven't read yet called "Through Their Own Eyes: Liturgy as the Byzantines Saw It" - I'm very interested in its approach on the subject (it's by Taft, who's one of the premiere Liturgics scholars of the modern era).
There are some simple Q & A books by Professor Ioannis Fontoulis in Greece, but they haven't been translated into English yet. They were written as responses to questions and published in a local newspaper (and eventually complied for the book). If you had access to one or more of these books, and someone to translate them for you, you'd benefit greatly.