One fork says, "Axle to Crown Length : 356mm (LC-21)"
3Rensho / TANGE Aero Front Fork

Another says, "Axle to Crown Length : 375mm"
Kalavinka / TANGE Straight Front Fork

There is a 19mm difference in axle to crown distance between the two. Why? Does it impact where the brakes mount in relation to the rim/braking surface or is the pad adjustment enough to make up for it? Does it impact handling positively or negatively? Aesthetics?

What does LC-21 mean? Is that a spec or a standard?

I have no idea about the weight of steel forks. The 3Rensho says 872 grams (1.92 Lbs). The fork that comes with the Soma Rush is listed on the website as 2.2 Lbs. These are examples because they are the only steel track forks I could find where weight is listed. Can anyone ballpark these weights for me? In terms of steel track forks, what is considered really light, average, heavy?

100mm spacing... 9mm dropouts.... crown race size.... steerer length.... rake... 1" threadless is what I need... I understand these concepts but as we say in the IT industry, I know just enough to be dangerous.

So what else do I need to know that I'm not asking?