Advice on Quizzes in Moodle
Question Banks and Categories
Organizing your question bank categories before you start creating questions will save you grief down the road. It will also make it much easier to select a certain number of random questions from a particular category.
Consider having some kind of naming convention that allows you to determine where a question comes from and what topic it covers.
In the Moodle question bank there are different icons for different question types so that doesn't need to be part of the title, but chapter number or textbook name can be helpful - especially when you haven't followed the next suggestion.
Question Bank Maintenance
Just like a well-kept garden, a Moodle question bank can benefit from occasional weeding and pruning. Before you import a whole new set of questions from the new version of the textbook, consider removing the old questions and categories. This will make quiz creation a much less confusing process.