Is it possible to block flash banner ads, as well?
Yes, it is. Go here or here to learn how. An even easier way is to use Adblock, an add-on that greatly improves Mozilla’s ad-blocking capabilities. Note that Adblock in its current state just hides the ads, i.e. it still downloads them. They are working on being able to not download the specified ads at all, which should greatly improve surfing the Internet for modem users.
