I just checked my packaged mix, and the ingredients are spices, salt, garlic powder, onion powder. sugars are 0. Check your ingredients, if there are no starches or flours, and no sugars, you should be fine. I use it with no incident. If your mix isn`t legal you can also do a homemade taco seasoning.
Re the supercharged book, yes that`s the one I have. Its his newest one so the food lists are more accurate (more dairy etc), though I did get out the first one from the libraray after because reading about the plan keeps me motivated , plus I wanted to see if I was missing anything. I found the first book better written (more actual book instead of recipes and exercises) but the principles are the same, there is a lot of repitition.
In short you don`t need both books, but you may at some point want to read the original as well.