I would definitely go to a local store here named Shortt supply.  Shortt supply is located in downtown Hood River and not only has all of the latest gear and things to help prepare you on your long hike, but they would also have firsthand knowledge of all the best places to hike as well as weather information and other valuable things that you can purchase such as a new book that I have seen here locally that is for sale in many places is called the Gorge guides.