How 'based' is Zemmour, on a scale of, say, 1-10?

Probably an 8, or maybe a 9.

Also, how is Zemmour framing the Great Replacement? If it is not (merely) an attempt at a Leftist power grab, is it... ethnomasochism (White Leftists seeing it as a tool to destroy their own racial in-group in the hope that it will entrench atomized individualism and/or because they want Whites to be punished for their ancestors' 'sins'?) Does he attribute an anti-capitalist element to it (importation of cheap labour, etc.?) or focus solely on White Leftist motivations (pathological altruism, White guilt, White saviour complex, etc.) and how it's in non-white interests?

He actually mentions both. He sees a perverse alliance between white leftists and capitalism, which is true.

Also, how J-woke is he? Does he, like Gottfried, bifurcate 'merchants' into 'good' and 'bad'? Or does he go further and claim that yehudi are bad more generally?

The first.