Hi Stephen,
Of course, they're not "dopey" questions, we all started out not knowing about Quiz, QuizPort, etc. and we found out a lot by asking questions on these forums. The naming of "activities" is rather confusing.
Moodle calls "activities" tools which allow some kind of interactivity by the student, either with the content or with other participants, or both. They're also sometimes called "plugins" or "modules". When you click on "Add an activity..." you see a list of such activites. This is what I see on my 1.9 Moodle site yours will be slightly different depending on what contributed modules you've added.

Quiz is a "native" Moodle module which creates different types of interactive questions that are stored in a question bank. To make a Quiz, a number of questions are selected from the question bank.
Hot Potatoes (nothing to do with Moodle) is a piece of software which allows you to easily create quizzes on your computer. These quizzes can be uploaded to Moodle and integrated via either of two modules in Moodle 1.9:
Hot Potatoes Quiz which is a core module in Moodle 1.9 - the administrator just has to activate it.
QuizPort which is a contributed module in Moodle 1.9 - the administrator has to download and install it.
After being uploaded, Hot Potatoes quizzes can also be imported into Quiz. (The Quiz forum is the place to ask for help in doing this.)
Gordon has recently written a message listing some of the advantages of presenting Hot Potatoes exercises through Quiz, QuizPort and the Hot Potatoes Quiz modules. It's at the end of this discussion.
Here are two links to the same quiz, one presented through the Quiz module, and one through the Hot Potatoes Quiz module:
Trivia Quiz as a Quiz (you see it as a Preview because you're not enrolled in the course).
Trivia Quiz as a Hot Potatoes Quiz
Sorry they're in French.
HTH,
Glenys