Hi there! We have a wonderful and extensive booklist section dedicated to the First World War. Here is the section on causes and tensions. I hope it is of some help.

As to your second question, an essential part of the conflict is to treat it as a world war, and not just a war that was fought in Europe by white Europeans. Consider the war, for example, out of the perspective of minorities and non-Europeans that fought and shared the same trenches as white soldiers.