Even in the United States we have too many gun-free zones and cities. It might have made a difference in the restaurant, but even here, the concert would have been a gun-free zone. Perhaps promoters of such events should be required to have four or five strategically placed sharpshooter with rifles with scopes, if it is a gun-free zone. A properly placed head-shot would even prevent a suicide bomber from setting himself off.
Um, no. Usually suicide bombers use deadman switches to detonate their device (if it's not detonated remotely by a confederate). The best snipers can do against suicide bombers is take them out when they are near fewer victims than otherwise.