Believe me, they can handle hitting the concrete. Mine hit the tarmac at triple digit speeds when I crashed on my motorcycle. Still works like the day I bought it.
I have the Hero 2, which I believe the Hero 4 is out now. Hero 2 would only do the fish eye view which was good for what I intended, but not sure if the Hero 4 offers a more standard view?
Also, check the various GoPro website for different mounting options. Many of these are not included with the standard GoPro package. And these mounts are generally not that costly either.
Also, buy a second battery. I would get about 4 hours from a battery, then I could place the second charged battery to finish an 8 hour day at the track.