hi greg,
what is the best way to remove frags from plugs/discs that they have been delivered on? depends on the coral. For things like zoas and ricordia and mushrooms, i just leave them on the plug and glue the plug where i want them. They will grow larger and overrun the plug or disc over time and you won't know its there. For sps and some others, if the frag has encrusted the plug, i will break off the plug but try not to damage the encrusted part. It it hasn't encrusted, i just pop the frag off. For some, you can take a pair of wire cutters and snap the plug with them.
what is the chance of damaging them in the process? usually pretty low, just be careful!!
i'm just working on my rockscaping right now. When the water clears, i'll post some photos for your feedback.
Wayne.