And the "electric signal" is an electromagnetic wave- also known as light. Nowhere did they imply the speed of light in a vacuum, the speed of light in copper is an equally valid interpretation.
No, it's not. If it were, you'd have photons moving through your copper wire, which would be quite the sensation!
A moving electron does create a change in the electromagnetic field, however, so maybe that's where your confusion stems from?
[0] https://en.m.wikipedia.org/wiki/Speed_of_electricity
[1] http://www.wolframalpha.com/input/?i=c%2F5ghz
Edit: if the chips were much larger. Smaller chips can go faster without becoming antennae.