I have to side with #4. The answer to this question lies in a successful understanding of the differences between absurdism and existentialism which are two terms that are often confused or considered to be synonymous. Camus is definitely an absurdist author, but I think there is a sufficient case to argue that he was not existentialist as he maintained. Of course, this remains a heated discussion point.
While absurdism may be subsumed under existentialism, existentialism isn't necessarily a part of absurdism. Camus definitely felt the absurdism of the world but rejected early twentieth century tendencies of negativistic reactions to the absurd universe. Some negativistic reactions he rejected were the absolutism of totalitarianism and the despair of existentialism. While acknowledging an absurd universe, Camus sought a positive expression of human dignity and individualism.
Sometimes authors don't want to be labeled because they want their readers to approach their works with an open mind. Perhaps Camus doesn’t want to be locked into one philosophy, and wants readers to experience his work as it is, without expecting something specific from it.
Total existentialist. I think you are asking if he is one. I think so. His book The Stranger completely examines tenants of existentialism from start to finish. If social order, responsibility for actions, and influence from others are all lost according to existentialism, then Camus certainly is existentialist. He presents Meursault as one who detaches completely from society and family, but will still get his own immediate needs met. Meursault also cares nothing for the life he took, or the concept of repentance that the preacher so desperately tries to get him to have by the end of the book. His own life seems worth nothing to him.
Often people claim to be one thing but their actions demonstrate them to be another. Sure, he could have created a character and that's all, but authors' attitudes and beliefs come through in their writing... they can't help it. That's just my opinion, of course.