I see that no-one has yet attempted to answer your query, so here's my advice.
Your interpretation of the meaning and usage of "To think.." is correct.
As to the remainder of the passages you quoted, I have to admit that (despite a lifetime's experience of reading English literature) I am no closer than you at fathoming the exact meaning of the particular phrases. Don't worry about it. You will often find that in these sorts of fantasy stories, the writers routinely use words and phrases in ways far removed from their normal usage, in the belief that this adds to the "atmosphere" of the piece. If you try to burrow down to the exact meaning of every word, phrase, or even passage, you will waste a great deal of your time. Much better to just go with the flow, and enjoy (?) the story as a whole!
Interested in Language