Nothing about your drilling adventures, but I have found that frag plugs are the spawn of Satan. Almost all the nasties come on the plug, not the coral. I always cut frags off of plugs, always. Just not worth it to me.
I also despise plugs with lugs. I get oceans wonders hexagon plugs (they are flat with no lug) and large discs or squares. I rinse them all off and just toss them in the sump for future use, allowing them to season over time.
Whenever I get a frag, I snip it above the plug and the plug goes in the trash. I glue the frag on to my own seasoned discs that I pull from the sump.
As far as gluing them to rocks, I get packs of single use super glue gel tubes and cotton balls. Squirt I little glue on a base, rip off a little bit of cotton ball, stick it to the base, smother the cotton in glue, and then wiggle it in place on the rock work (after using a stiff tooth brush to clean the base and rock).