Assigning variables in inspector

What happens when I assign a MonoBehaviour Object variable via inspector? Is it instantiated on game start with active being set to false? If not is there a way to mimic inspector variable assignment in script?

Nothing happens when you assign an object to a variable in the inspector, aside from the variable now containing a reference to that object. No instantiations or anything occur. There are various ways of getting references in code, such as GameObject.Find, FindObjectOfType, Resources.Load, etc.