A pal of mine just had a crash. Got blindsided by a bus. Was in a coma for 3 days. Was wearing a full face helmet. Docs told him that if he were wearing anything else his head would have exploded. Even with a full helmet he shattered the entire left side of his face which is now plastic where bone should be. I advise NOT wearing a half helmet. We spend all kinds of dough on bike mods to go fasterbut then skimp on protection, trying to find cheap helmets that are not SNELL approved.
As far as backpacks go I have the Ogio No Drag mc backpack. Semi rigid construction, aerodynamic, suited for hydration as well as audio. It even has a slip case for a laptop.
http://www.motorcycle-superstore.com/mobile/ItemPage.aspx?DivisionGroupId=1&DivisionId=4&DepartmentId=67&ItemStyleId=11414Awesome durable and stylish pack.