I think Changez includes these details at the start of his narrative to display to the American how much at one point in time Changez accepted the promises and possibilities of what it means to be American.  In seeing Changez at this point in his life in Lahore, it is easy to forget that Changez at a particular moment did fully embrace what America meant to both he and the external world.  In discussing both his experiences in America as a student and the exposition to move him to such a point, Changez makes it clear that he was the embodiment of what the allure of America means to so many around the world and, specifically, to Changez.  It is important to include these details to reflect how much disillusion Changez ends up experiencing.  It adds depth to his characterization to see him repel something that he used to be.  Additionally, it speaks to the complex nature of fundamentalism against the United States.  Many people who now speak of the harshest conditions in opposition to the United States represented at one point in time alignment with the United States.  Osama Bin Laden and Saddam Hussein are two of many people who were benefactors of America or were able to embrace the idea of what America represents at different points in their narrative.  In this, Hamid seeks to make clear that there is a complex discussion that accompanies the topics of fundamentalism and terrorism, one that transcends easy answers and simple labels.  Changez would certainly represent this, evidenced in his detailing of his past to the American.