Is it typically better to have one style sheet that all of the pages on a site reference, making it very large; or is it better to have an individual style sheet for each page, even though you may be negating the purpose of using classes?
For what you've described you are better off having one style sheet. That way the browser can cache it and it will speed up the loading of your pages. But, there are times when you'll want to have a special style sheet for a page or two that is separate from the main one. In that case, that page may either have it's own style sheet or it can have two stylesheets if the second one will compliment the first.