The Arthritis book is excellent. It's concise and has plenty of great information about what arthritis really is, and how to deal with it. I use this book because for me, joint pain is more present in my life than fatigue, although that's an issue as well. Anyway, the book is highly recommended.
As for the secretor test, it's a way to fine-tune the diet for your needs. It's also a great way to help raise your compliance level, as you have a better idea of which foods are highly beneficial and which are avoids. It's interesting to see what your status is too. I was positive my test would show nonsecretor--nope! But for all intents and purposes, I eat like a nonnie because I'm so sensitive to grains, legumes and sugar that I'm better off eating that way. I just use secretor values for beneficial/avoid foods.
Hope this helps.