The third questions just, because I initially got 1 but then i re-did my math and got 1/2 so I'm not sure if I computed that right (my math might have been off).

Yes, the answer is 1/2, so your math is fine.

What does normalizing look like visually? Why do we need this when specifying the surface normal in OpenGL?

Great question! Normalizing keeps the arrow pointing in the same direction, but changes its length so that it's 1 unit long. It's the "standard size", and it's reasonable to think of "normalizing" as a synonym for "standardizing".

Internally, Threejs does normalize the normal vectors, so you don't have to worry about this.

not at the moment, i dont love math (repsect to those who do)

I understand your feeling, and I'm sure many people share it.