Jenn,
First, congrats on your roo getting POW! He's a handsome one!
I have the 2006 Edition of the ABA SOP (color edition), and refer to it constantly, and absolutely recommend it for anyone that is serious about breeding to the SOP or showing.
Keep in mind that "Cochin" is the breed, and "Variety" refers to the different color varieties, i.e. Mottled. Chris09 gave you a good summary of the description of Mottled; you will find the full text in the SOP - which varies slightly for males and females.
You may decide at a later date that while staying with Bantam Cochins, you may want to branch out and obtain different color varieties. Having all the Plummage descriptions available is a must - especially if you intend to buy anything besides pet quality.
Another valuable tool in the SOP is the "General Scale of Points". This is the scoring system that judges use for Shape, Color, Weight and Condition. Being able to judge your birds' Shape and Color according to the SOP is especially useful, not only in selecting your show birds, but also can help you determine which ones to keep for breeding and which to cull, as it tells you which factors/traits carry the most weight in scoring.
IMHO, it's well worth the money.