I wouldn't touch it unless you know what kind it is. Some are venemous or at the very least a spine can break off in your skin and cause an infection.
I have 4 in my tanks (1 tuxedo, 2 pincushion and another large back one, don't know what kind) and they are perfectly happy cleaning the sides of the tank and my rock. I do once a week, give them a piece of nori. They seem to like it, but I don't think you need to feed them. I have a long grabbing tool, I feed them with that.
Enjoy, I love my urchins!!