Heat would be a massive issue with more layers, right?
A big problem (and also probably why they're so thin) is that at a certain size latency becomes a huge issue. This is where clock speed increases come into play (electrons move faster) along with die decreases (electrons can travel shorter distances).
If you can run 100mph, but you have to run 200 miles vs. someone who can walk 1mph, but only has to walk 10 feet... I wish I had some more concrete examples but I can't come find anything off the top of my head.
Sort of. But if you reduce resistance you increase heat since more current will flow.
On the other hand, if you increase resistance AND also keep the current the same then you'll get more heat. But! to keep that current constant you must increase the voltage.
So it's not so simple as "resistance = heat".
> The more metal the electricity is flowing through, the more material there is incur resistance
Depends on if the metal is in parallel or series. If in parallel, then the more metal the lower the resistance, if in series then higher resistance.
> If so, then more layers = more heat.
Right result, wrong method of getting there. More layers (which would be in parallel) would be less resistance. But less resistance means more current flow (since they'll keep the voltage the same), and more current flow means more heat.