Wait until healed. Rarely should one dance with a fractured ankle until cleared by his/her physician. Most ankle fractures heal in 4-12 weeks, and i then prescribe physical therapy for several weeks before a patient can return to dancing, power walking, jogging or sports. Prior to that return, I do usually prescribe a brace (lace-up/velcro or semi-rigid) to prevent the ankle from rolling in/out and re-injury.
Depends.... This depends whether the fracture is stable or not. You will need to rest a broken ankle for a period of time before returning to activities such as dancing. I would seek the care of an orthopedic foot and ankle surgeon in your area. They can provide the appropriate treatment. One in your area can be found at aofas.Org.