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.
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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