| As kp mentioned there are various tools available to drive in ground rods. I have used a 3 or 5 pound sledge hammer using a pair of channel locks to keep the rod still and keep my hands away from the hammer.
By damage, do you mean the mushrooming from hammering? If you are using the acorn type ground clamp, I slide those over the rod first. Other wise if the mushroom prevents a clamp from slipping over, just cut that bit of rod off.
When two rods are needed, both rods must be no closer that 6 feet apart. Which means not 5'11" but more than 6 six feet. Each must connect together with the ground wire from the equipment being grounded.
If you encounter ledge, then you can drive each rod in at an angle no more than 45 Degree. If there is ledge too high to grade. then the rods can be buried in a trench no less than two feet deep, again six feet apart.
The top of each rod must below grade, so the wire and connector is below grade, and the connectior must be rated for direct burial. | 
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