I think I'll jump in with a serious answer here...
1. How long do they last? As long as you take care of it, it should last until you hit something hard. As long as you're in a wide open area (which I assume you would be since I doubt you'd be racing it, no offense), the only thing you need to really worry about would be normal wear and tear, unless the car somehow comes off the ground. If you're running near curbs or something solid, parts are more likely to break. Trust me, car vs. curb, curb wins.
2. Sure, you *could* ramp an onroad car from the street to the grass. Then again, you could also put your hand into a blender and turn it on. I wouldn't recommend it
