None of your propositions reflect any claims made by ethical fitnessism.

Ethical fitnessism is a normal moral theory just as hedonistic utilitarianism, but with differences in its meta-ethics and intrinsic value. It violates neither Hume’s law nor the naturalistic fallacy. It is not the case that nature or evolution implies that ethical fitnessism is right in any higher meaning.

Fitnessism has no special naturalistic definition of the word 'should'. It uses 'should' in the same sense as utilitarianism does.

For a further description and explanation of fitnessism please see my response to DeVliegendeHollander.