The questions in this poem are rhetorical. They are not meant to be answered as the narrator provides us with his own answers to the questions.
The first question asked is:"Does it matter?-losing your legs?" The narrator then provides reasons why it might not, but clearly the narrator is showing the blow to one's pride and self-sufficiency would matter.
The second question asked is: "Does it matter?-losing you sight?" Once again, the irony of the narrator's voice is clear when showing the helplessness and dependency one might experience. Memories of sight would be all one had left.
The third question asked is: "Do they matter-those dreams in the pit?" Clearly, the dreams one must give up as a result of war do matter, even if no one is concerned with the consequences.
So the questions are designed to convey the irony of the narrators questions when juxtaposed with the narrator's true feelings.