Hello,
You can find documentation in CHM format on this
page, see bottom of page please. Regarding your questions, quiz categories are using for diviing quizzes by themes. For example you want to create two quiz about animals and two quiz about geographic and want to create menu point to quizzes about animals and another menu point to quizzes about geographic. In this case you can create 'Animals' and 'Geographic' quiz categories and assign quizzes about animals to 'Animals' quiz category and quizzes about geographic to 'Georaphic' quizzes category and then create menu points to necessary categories through standard Joomla! creation menu item page. Users also will see name of quiz categories and quizzes from each categories on quiz list page. Question categories are using inside quiz that divide question in quiz by categories. For example you are creating quiz about animal and want to add 3 questions about pet and 5 questions about wild animals. In this case you can create 2 questions categories for this quiz, 'Pet' and 'Wild Animals' and assign appropriate questions to necessary categories. It helps divide questions inside quiz by themes and you can also set some settings in question category, for example time limit for questions from this question category and how many questions will be selected from this category for user quiz. If you want to create shared questions, use question bank for this purpose. You can create questions in question bank and then add them to different quizzes and if you change question from bank, this changes will be applied to all quiestions from quizzs which are based on changed questions from bank.
Regards,
ARI Soft