I didn't intend to imply that nothing Marx ever did was accurate or useful. But I would say that before you can get anything out of, say, the Labor Theory of Value, you have to do a lot of translating into real world conditions of economic behavior.

Yes, he did do some useful research. He then did a terrible job of applying the results.

As for the rest, we're in considerable disagreement. Exploring it would take us well outside the boundaries of this site. We can agree to disagree.