Any hook will work. Most of my hookup is using an treble hook. But that one work well to. 20lb leader is enough unless you let them drive down to the rocks.
I used mustad 1/0 circle hooks on a 1oz carolina rig. 25lb braid and a 50lb big game mono leader. And yes, fiddler crabs work for me. If you take off the claw they ...more work better. Drop it to the bottom..