RE: spine
With most easton carbon arrows the model number is the amount of spine deflection the arrow has, which is the actual spine of the arrow.
When talking arrow spine the lower the number the stiffer the arrow, but the model numbers don't always correspond, you need to look up the actual spine deflection for that arrow.
Spine is measured by putting an arrow on two contact points (28 inches apart I believe, but could be wrong) and suspending a specific weight in the middle ( can't remember what it is off the top of my head) and measuring the amount of flex or deflection that it has. A weaker arrow will obviously flex more than a stiffer one thus giving it a higher number. The measurement is in thousands of an inch. An easton 400 series arrow will have .400" deflection.
Paul