Regarding anarchism and communism, I'd like to bring up an interesting point:
ANARCHO-COMMUNISM.
Yes it exists.
Definition: "advocates the abolition of the State and capitalism in favor of a horizontal network of voluntary associations, workers' councils and/or commons through which everyone will be free to satisfy their needs".
So, even though they are polar opposites, Anarchism can be reconciled with Communism in a certain sense.
Just thought I'd bring that up.