Confused about spark plug wires

[Decolliber]

Shortly after buying my 911 four years ago I replaced the spark plug wires because the OEM ones were frayed and a connector cracked. The ones I bought were "Blue Ignitors" from www.rapidparts.com:
Blue Igniters™ are the perfect upgrade for your ignition system. They offer high performance, good looks and feature a lifetime warranty. Blue Igniters™ are made with a 19 strand, individually tinned copper core, wrapped with a double layer of virgin silicone insulation which resists extreme heat and stays pliable even under very cold conditions. This double-layered, 7mm bonded silicone insulation eliminates the moisture found between the insulation layers of most of the other wires on the market today.
(the blurb went on to say that some people wrongly think that 8mm wires are better than 7mm wires...)

Looking at Pelican's range of plug wires I get the impression that thicker wires are "better" (e.g., Magnecor). But the measures of 7, 8 or 8.5mm is a measure of the total diameter, including insulation (right?). So wider does not necessarily mean wire that is thicker or a better conductor.

Do all plug wires have the same gauge of wire underneath the insulation?
If not, why don't the plug wire specs state wire gauge?
Isn't thicker wire always a better conductor?
Does it matter how many strands of wire?
Since silver and gold are better conductors, why doesn't someone make plug wires coated in silver of gold. You can buy silver stereo speaker and composite cables (very expensive of course).

[Superman]

The voltage is so high in your ignition system that it can be conducted by nearly anything. Those sparks are so excited that they desperately want to go to ground. I'd say the insulation of the wire is more important than the conductor. Still, 8mm is not necessarily better than 7mm.

[no substitute]

Read some of the plug wire theory on the Magnecore site. It is contradictory to what many of the companies that try to sell you wires say. Magnecore is a "fav" of many racers. Carquest wire with factory ends will work very well, too.