measure units in script

if I drop a cube from the game in to the screen it measures 1x1x1 correct and if I change it to 100x1x1 the cube will measure 100 units on the X and 1 unit on the y and z?
if this is all true then if I use a cube to measure distance of 100 units then if I cast a ray for 100, would they be equal to the same distance?

yes, you could just set it up and test it.

use Debug.DrawLine() and Debug.DrawRay() to visualize your raycast.