Laser donīt lose energy on their travel....it doesnīt matter whether it hits you from 100 or 1000 meters
That depends on the atmospheric conditions and quality of the lens. There will be some attenuation as the beam hits particles and diffracts. The more visible the path of the beam itself in the atmosphere (smoke, fog, mist) the more it is attenuating, but it is vastly different from the inverse square law that we can apply to normal light sources.