Maatsuah - The Heart Sutra is profound, and what TNH writes about it is illuminating, but it's not informative on the kundalini process. He's a Buddhist; kundalini emerges (slithers?) from the Hindu tradition. I came to AYP in search of info on kundalini as well, and there's a wealth of info in Yogani's lessons. Have you bought his book with the lessons? It's available at Amazon (or online, but I don't like reading online). I highly recommend it, as it's extremely informative and well written. As soon as you start reading about or experiencing Shakti, it's not long til you're reading and experiencing Shiva, and there's good info on that as well.
Another book that I found very helpful was "Kundalini and the Evolution of Consciousness" by Solomae Sananda. She's a bit of a quack, and the book is terribly written, but other than that (!!) it helped to understand some the process that one goes through during a kundalini awakening. That's the only book by her that I'd recommend, btw.
