There are many misunderstandings about Catholicism, including among Catholics themselves. This dynamic is true for just about any belief system - religious, political, social, etc. It's a reflection of our imperfect humanity.
Marcus Guevara put a list together called 7 Things Every Protestant Should Know About Catholicism.He prepared it in December 2013, and it is still worth passing along. I just learned of it. The author focuses on Protestants, but with a minor number of edits, similar lists could be prepared for other sects, like Jew, Atheist, Muslim -- and then they could all be combined for the general public, or so I believe.