I've recently read the biography "Life of Milarepa", which might be of some interest to you..
Here's the synopsis for the 2010 translation by Tsangnyon Heruka, released by Penguin Classics
A new translation of the classic biography of the most renowned saint in Tibetan Buddhist history
The Life of Milarepa is one of the most beloved stories of the Tibetan people and a great literary example of the contemplative life. This biography, a dramatic tale from a culture now in crisis, can be read on several levels. A personal and moving introduction to Tibetan Buddhism, it is also a detailed guide to the search for liberation. It presents a quest for purification and buddhahood in a single lifetime, tracing the path of a great sinner who became a great saint. It is also a powerfully evocative narrative, full of magic, miracles, suspense, and humor, while reflecting the religious and social life of medieval Tibet.
You can find this on amazon,for example..
This is the one I read, I don't know it might compare to other translations, but it was pretty good. There's also a movie about Milarepa's descent into evil ways, the first half of his story, but it doesnt quite follow the script, in the way of movies heh
As for zen understanding and tibetan buddhism, my Lama mentioned to me that Mahamudra practice in tibetan buddhism is the equivalent, and from what I've studied on it so far, the same "things" apply, just formulated in different ways, and a lot more structured.. My "understanding" of patriarchal zen certainly helps me get what they are talking about!
There's lots of "dharma gifted" free texts on that subject, online in spiritual text repositories
Here's a sample out of "The Gelug/Kagyu Tradition Of Mahamudra [Dalai Lama, Alexander Berzin]", which i've seen as ebook and website documents:
The mahamudra realization is never "Just live naturally like an animal. Just see and hear, and
have no thoughts." That is not it at all. Furthermore, even if we are able, through the initial
mahamudra methods, to achieve the level of attainment at which we are not greatly disturbed
by the contents of our experience, we should not fool ourselves into thinking that mahamudra
practice is so simple, or that this initial level is all that there is. It is a step in the correct
direction - a very big step - but it is not yet a profound understanding of mahamudra. To go
deeper into mahamudra practice, we need to develop shamata, a serenely stilled and settled
state of mind totally absorbed with single-pointed concentration on mind itself, first
specifically on its conventional nature as mere arising and engaging. The First Panchen Lama,
in A Root Text for the Glorious Gelug-Kagyu Tradition of Mahamudra, begins his
presentation of mahamudra meditation at this point.