Different departments weigh different parts of the application differently. I don't think that there's a universal baseline score for GREs. GREs are important if they are very low or very high. In my department (University of Massachusetts), we weigh the writing sample fairly heavily. If a graduate department is unfamiliar with your undergraduate institution or with your recommenders, then GREs and writing samples become more important. I'd recommend applying to a range of universities, so that you'll have some back-ups.

I'm not sure what you include within the scope of 'knowledge'. Philosophy? Poetry? If the political atmosphere had been different in any number of ways, different people would have produced philosophy and poetry. It is reasonable to suppose that different people with different sensibilities would have pursued different projects and had different ideas. You wonder whether it's productive to ask your question. I think that any answer will be vague (as above) unless you have a well-worked-out theory of gender (or race or class or....) and a good historical understanding that allows you to apply the theory to the past.

I agree with Louise Antony on this matter. In my opinion, the contribution of feminism is to social justice, rather than to the theory of knowledge.