As a writer, some of this strikes me as dumb. There are a lot of people who aren't "writers" that I'd be glad to hire. Why would you grill someone on the rules in the Elements of Style? They can look that sort of thing up. If anything, I'd be more interested to see if they absorbed the real lessons in the Elements of Style. (Hint: Not the rules.) Also:

"We have found that we are able to hire great writer from this process, who are able to create award winning content, whether it is a short article or a book."

Hire a copy editor.