The same basic kart as is used in Sprint racing can be used in Speedway racing. However, there are specialized chassis' available to optimize weight distribution. These are called 'left-turn only' or 'offset' karts. Another type of specialized chassis is known as a Kage or Champ kart. The increased protection make these karts about as safe as racing can be while still offering all the action.
Average speeds are considerably less.
Races typically last 15-30 laps. Again, speed costs. Tracks are usually not listed. If that fails, you can contact the major sanctioning bodies. I recommend you go to the tracks nearest you and observe the action.