I believe it resembles a parsnip - same color but thinner and longer. Advice: If you're going to mess with it, wear rubber gloves and don't touch your eyes. It burns like hell and the acid will do a number on your skin without the gloves. That said, use sparingly and good luck. As to selecting, smooth, unblemished and solid. As to storage, no idea but probably like ginger.
It looks like a cross between parsnip and ginger. Avoid withered and brownish, dry looking roots and any that are sprouting. Should be creamy white inside. I have never worn gloves but I don't touch my face when chopping. It's a hard root, it doesn't burn like capsacian in peppers. To process you peel it then chop or grate. I cut it into chunks then throw it in the food processor. Mix with salt and white vinegar. The longer amount of time you wait between the grating and adding the vinegar, the "hotter" it will be. Homemade is a revelation. It is not mushy like the jarred kind can be. We use it in Deviled Eggs, on Prime Rib, Corned Beef and Potato Pancakes. It is fantastic in homemade Seafood Cocktail Sauce for shrimp cocktail or raw clams. Yum.