Let me see if I can answer. I'm no expert but this is just my take on things and my own experience:

1.Immune System:

I've noticed that my usual seasonal pollen allergies have improved a LOT this year. Last year I could barely function in the springtime, but this year hardly a sneeze. The Paleo is definitely helping my immune system. Plus I haven't caught flu this year.


2. Scary Part of the Book...

Well, I've cheated on this diet at times, like by having a slice of pizza when we were at a friend's house and that was all she gave us. I find that it would be terribly rude to refuse to eat at her table after going to the trouble of making it. So in this kind of situation I have flour based products and you know what? Nothing bad happens. It's the SUGAR that creates havoc with me, not the flour. If you find you have some flour, just do strict Paleo for a few days and get back into your routine.


3. Enzymes and Constipation:

Interesting questions. I don't eat Flax Seeds, so I can't help with that one. . I just have lots of fiber rich veggies like green asparagus and that sort of thing. I also use olive oil on salads, etc. Lots of it. That takes care of constipation. In any case, you might find you "go" less on Paleo, as you're probably using the food intake to its best advantage and not having to get rid of so much waste. This is just my own theory, I haven't read it anywhere.

Good luck!!!