Yes you can buy books and other items from the NCRS bookstore without being a member. There is a significant discount for members though. Depending on what you already have you may be able to save all or most of the cost of membership by joining. I don't know what other automotive interests you have but if your solid axle Corvette and it's originality is your main long term interest there are certain things you need. A ST12 factory service manual, a 1962 Factory Assembly manual and a NCRS 1961-62 Technical Information
Manual and Judging Guide, where you will find all of the answers to your numbers questions. The NCRS is so much more than just another car club. There is close to 4 decades of research and documentation available through the NCRS and I doubt there is any question that can be asked that hasn't been asked before. Every article ever written in the Society magazine (The Corvette Restorer) on every area of your car is available on CD. The amount of knowledge is staggering. I can't imagine trying to restore or preserve one of these cars without being an NCRS member. The on line Tech Board will give you near instant answers to questions by many members that have been there and done that many times.
The Birthday book, I believe is a guide to help you determine what day your car was built. I don't know what else is in it. Your serial number does not tell you anything about how your car was originally equipped. Most all components from the engine to the clock have markings and date stamps that relate to the production configuration and build date of your car. The big one is the stamped pad at the front of the passenger side cylinder head. There will be a serial number directive that should match the vin on the steering column. That will show or not that it has the original engine. That's the big one.
Tom