I haven't done any of these type races, but I plan to do a Warrior Dash in the fall and a ToughMudder after Christmas if I enjoy the warrior dash. I think this looks like a blast.
I'm not sure about training. I do know that I became a friendof the Spartan race on facebook and they post some scary workouts most weeks. I haven't tried any yet, but am thinking about adding one/week.
Last week they posted ths workout: run 1 mile/10 pushup/10 pullups/20 crunches -then repeat x8