Probably the easiest way for me to answer this, or at least part of this, is to refer you to the www.eastonarchery.com . They have a very nice guide to help you with the tuning process. I would link you directly to the guide but my place of employment has decided to block that site from our network.

The term "spine" in reference to an arrow refers to how stiff or how weak the arrow is for any given setup. In other words, how much it flexs or bends upon release of the bowstring. Different setups require different spined arrows in order to achieve the best accuracy and penetration.

As for proper arrow weight, I tend to prefer to stick with arrows weighing no less than 6 grains per pound of draw weight ( for example....a 70 pound bow x 6 grains per pound = 420 grains) as I have a longer than average draw length and shoot a heavier draw weight. However, that is also going to varyper individualdepending on a variety of factors.

Hope this was somewhat helpful.