CC Creative Commons

How do the ideals of Creative Commons relate to the realities of life in the digital world?
I must admit that I didn’t even realize that copyright was instant. I thought that you had to apply for it. The CC appeals to me because in education it can be really confusing when you want to stage a play or make a film for your class and you need to borrow from others. I really like the idea that I can make it official that my online photos or writing can be shared.

What sort of Creative Commons license should we apply to the course wiki?
I think this one  Attribution should be used for our course wiki - “You let others copy, distribute, display, and perform your copyrighted work — and derivative works based upon it — but only if they give credit the way you request”. This allows artistic freedom but gives credit to the author.
I have one question for you all;
How can you tell who is the true author? What happens if I use something from the Internet with CC that has been plagiarized from somewhere else? I mean how could I know?
And, what if I created a similar artifact to someone else and then made it CC, and then the other person found out and got angry. I mean it could happen right?