There is no class higher than First Class because first Class is the highest and the best.

First class, no sweat

No much difference between first class and first class ac. Only AC is the difference. First class does not have AC.

The correct phrase is "passed with first class". This indicates that the individual achieved a first-class degree or classification in their academic endeavor.

You cannot have a preceding class to the first class. There is no zeroth class.