Hi Ron! Happy to help :)
About your second question, I don't think Codex has anything to do with quantum computing. It has been fed with so much language+coding data that it has become a master in knowing which words go with which.
It doesn't understand meaning in the sense we do, but it's an expert in the form and structure of language. That's how it can "interpret" ambiguous instructions.
About quantum computers being better suited for the task, I can't answer, as I'm not an expert on that topic! But I'd love to know if you find the answer!