Is there a universal formatting standard for writing CSS code? If not, what syntax in a CSS class is a browser reading first from a style sheet?

For example, in any given class, should the background-color come before or after the background-image and should the font attributes come after, or before, the text attributes?

I’ve been searching around the net for weeks in an effort to start optimizing my code for optimal load times, but alas, nothing.

No.

The things you need to be aware of are;
definitions are applied in "top down" order with the later ones taking precedence,
styles applied to an ID will overrule styles applied in a class on the same element

CSS order does NOT affect load or rendering times.