Use the copper mounting clamps I included with your element and just put the mounting screw threw the eyelet I put on the green wire. The copper will complete the circuit through the tube.
There is no danger from having the element touch the side of the copper tube. It is just a hot resistor at that point.
I recirc at full throttle during the mash. In other words I open the valves fully once I am doughed in. This helps maintain more even temps.
I power 1 element, 1 pump and 1 Love control from 1 15 amp outlet. I power another element and pump from a second circuit in my garage.
On a 5 gallon batch I see about 2 degrees per minute temp rise. Most days I set up before dinner, get everything running and go inside for an hour, when I come back out, I am ready to dough in, then I can disappear for another hour and put my son to bed.
I generally watch the sparge and boil fairly closely.