This link will give you all the info you need on Spark Plugs
http://www.ngksparkplugs.com/techinf...000&country=US
In addition to that let me try and explain the other points you have raised:
1) modern high-energy ignition: High energy coils being used on cars for a higher voltage and a shorter pulse, this allows for a larger gap between the points to aid ignition.
2) As for projected nose plugs: They are the standard plugs that look somehat like this:
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This is where the center point is raised from the body of the plug.
3) The top arch which acts as the second point is known as the ground strap.
In NOS / Forced Induction engines the temprature of the ground strap is about 70 to 100 degrees hotter than in normally aspirated engines. Hence this leads to the ground strap to start glowing(red hot) when it does it can cause premature ignition within the cylinder leading to misfiring, this can be reduced by using plugs that have a shorter ground strap
the image below illustrates the same:
Do also realise that spark plugs also dissapate heat from the cylinder to the engines head(like a metal spoon kept in boiling milk).