The difference between good and light, and evil and dark

Yes

That clears up a point of confusion I had for awhile, but it also begs a question:

So if Order is the natural order, the energy of the prime material plane, and that stuff everything is made of
Chaos is the energy of other planes, being the opposite of order means chaos energy isn't really a healthy thing to have around things in the prime material plane.

So what are the inherent qualities of light and dark?

Only the Abyss is made up from Chaos. The elemental planes are derived from their elements.

Light tends to make the days longer, sun hotter, etc.

Dark makes the nights longer, and winds colder, etc.