I'm sorry you are boggled. For question #1, what do you think "freedom of expression" means? Does it mean a church or a government or some other censor can decide what an artist can depict, or a speaker may say? If someone decides all of Picasso's cubist works are ugly, should they all be destroyed?
For the others, I'm sure you have text materials that have addressed these questions. For Duchamp, you might want to read this:
http://www.biography.com/people/marcel-duchamp-9280070
For the question about a Buddha statue, I have no idea. Certainly the artist will do his or her best, but religious fealty to the deity is something I know nothing about in Buddhism.
And if an artist is protesting something, do you suppose he WANTS to stir up controversy and make people aware of what he is protesting? Think about it. Is he/she just doing it for the fun of it, to put the work away in a closet somewhere?