I order my Nopalea opuntia cactus from www.rivenrock.com http://www.rivenrock.com/ediblecactus.htm
There are no spines/thorns on Nopalea.
I keep the pads in a plastic bag in the refrigerator. They'll keep for a month unwashed. I wash them in cold water and scrub them with a vegetable brush...
I had a Hermann's tortoise for 21 years who understood everything I said and used to talk to me. She had me trained. She was a character. But I've known male Hermann's who were aggressive and biters.
My Redfoot tortoises are Labrador Retrievers trapped in shells. They're smart and affectionate...