I am pulling on my Editor hat here to answer some of your questions.
All editor's quizzes are subject to the same scrutiny as non-editors, because inadvertent mistakes can crop up in even the best author's creations. Having said that, I would agree that a quiz by an editor is usually much easier to edit.
The qualifications for editorship are a lot more stringent now than when I was accepted about three years ago. The newer editors have had to jump through many hoops and are subject to scrutiny by more senior 'staff'.
I do not have the statistics available for gold members, but as these members pay a small fee, they tend to be less transient and therefore would probably create more quizzes. This would also hold true for editors.
Hope this helps.
The key to everything is patience. You get the chicken by hatching the egg, not smashing it.
Ex-Editor, Hobbies and Sports, and Forum Moderator