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The main source for the rough outline of Athenian demographics (noted in your outline, not in your main) is M.H. Hansen, Demography and Democracy, but I've made some adjustments on my own. There's also a bit of Beloch in there, as always.
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On the helots, I'd say that the balance of the current scholarship tends towards 'oppressed slave class' as opposed to 'regular serfs' but there is range, both in thinking about treatment to thinking about degree of class-struggle (cf. Cartledge w/ Talbert on that second point).
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