Hi Jim,
Have you looked at Learn With Kentico resource? When you are ready to take the exam, it first starts with 7 questions test exam to give you an idea of questions.
Anyway, it's quite open exam meaning that you can use documentation to find answers for the questions when you are unsure (which I know Sitecore doesn't allow and you literally have to remember all that). And the best preparation for the exam would be to complete Kentico courses from the learning portal and have a real experience with the platform on project or two.