I am looking for information on arrowroot used as a thickening agent in soups, sauces, and gravies. (Not as a substitute in baked goods)

I am on a LC diet and have allergies to foods such as wheat, corn, rice, barley, etc. My family does not join me in my LC quest.

I am looking for ways to decrease their consumption of refined carbs, especially wheat products.

My plan is to wean them gradually, so as not to meet too much resistance.

What is the carb count of arrowroot?
Is it known to trigger allergic reactions to those sensitive to wheat?
If it is a viable substitute, how do I cook with it?

These are just a few questions that come to my mind. Any extra info would be helpful.
Thanks!