... Visit the Navy Yard, and behold a marine, such a man as an American government can make, or such as it can make a man with its black arts — a mere shadow and reminiscence of humanity, a man laid out alive and standing, and already, as one may say, buried under arms with funeral accompaniments, though it may be
“Not a drum was heard, not a funeral note, As his corse to the rampart we hurried; Not a soldier discharged his farewell shot O’er the grave where our hero we buried.”
 The mass of men serve the state thus, not as men mainly, but as machines, with their bodies. They are the standing army, and the militia, jailers, constables, posse comitatus, etc. In most cases there is no free exercise whatever of the judgment or of the moral sense; but they put themselves on a level with wood and earth and stones; and wooden men can perhaps be manufactured that will serve the purpose as well.
The quote is from On the Duty of Civil Disobedience by Thoreau, I have several questions:
In the first paragraph, if "Visit the Navy Yard..." is a imperative sentence, does "such a man as an American government can make" modify "a marine"? There're two "such ... as ..." but they are asymmetric, what's the structure and how to understand this paragraph?
Does "thus" in the second paragraph mean "therefore" or "in this way, in the way that"?
In most cases there is no free exercise whatever of the judgment or of the moral sense; but they put themselves on a level with wood and earth and stones;
Does it mean "the state doesn't allow them to exert free exercise of ..." OR "they don't exert free exercise in the state"? How can I determine the subject in a general way?
What's the meaning of "but" here? Can I associate it with "no"?