Yucca Root and Stem

So, my partner dug up a large yucca plant from our yard, and it occurred to me to save the roots. I've also ended up with stems. Right now they are in a basin in the sun. What are your suggestions for preparing them for culinary/medicinal/cosmetic uses? (It appears to be Yucca filamentosa.)

I have heard of using it as a shampoo, and externally and internally for arthritis and pain-- but searches tend to yield ads to buy prepared capsules or products. I have loads of root and some stem, and I'm willing to prepare it-- how?

Also, is this type of yucca good for eating at all?