Hey Susan, although I don't have any hard data, recent open policy trends and the large amount of CC licensed works on the web suggest that CC licenses are becoming quite common in many circles, especially in education. I agree that education about the CC licenses hasn't quite caught up, which is why we're trying to change that with the School of Open! A lot of librarians and educators actually do incorporate CC license education into their curricula, however, like some of your peers who are taking this course!
Regarding attribution best practices, yes it would be a best practice to give credit to all creators of the work, but as reasonable to the medium and context. The attribution requirement is designed to be flexible. See this FAQ for more info.
How strictly a license is enforced is up to the licensor. (Keep in mind that this applies to any copyrightholder posting their work on the web, even if they don't use CC licenses.) Some licensors might sue, as in these very rare and far between court cases, but most licensors will simply request the user to correct his or her mistake (because it's usually just an oversight) and such cases are often quickly resolved with an email or tweet. One of the benefits of CC is a global community of CC creators and users that can help with recognizing when a work is being used improperly (or fantastically -- and then particularly creative reuse is a boon to the original creator).