Re 1, if that is the case why not support the Articles of Confederation instead?

I never said we should support it; I said we should care about it.

It would be silly to claim that anyone interested in FAI should be pro-Constitution; there were plenty of 18th century people who earnestly grappled with their version of the FAI problem and thought the Constitution was a bad idea. If you agree more with the anti-Federalists, fine! The point is that we should closely follow the results of the experiment, not that we should bark agreement with the particular set of hypotheses chosen by the Founding Fathers for extensive testing.