RE: Correct spine
Spine is very important with carbons. They tend to have a poor spine tolerance within a dozen. It really helps if someone can spine tune the arrows. Either that, or purchase the most expensive models, which tend to have better manufacturing tolerances. With carbons, I like to shoot them slightly stiff and with a high FOC. I also spine tune them. I can find little difference between my accuracy with either carbons or aluminums when doing this.
You can tune your bow to the spine of your current dozen, not only by changing tip weight, but you can also change the draw weight to affect spine. Shortening your arrow will also stiffen it.