1) Do Earths with dumber politicians have a better chance at FAI?

How much dumber? If we can make politicians marginally dumber in a way that slows down economic growth, or better yet decreases science funding while leaving economic growth intact, without this causing any other marginal change in stupid decisions relevant to FAI vs. UFAI, then sure. I can't think of any particular marginal changes I expect because I already expect almost all such decisions to be made incorrectly, but I worry that this is only a failure of my imagination on my part - that with even dumber politicians, things could always become unboundedly worse in ways I didn't even conceive.

2) Do Earths with anti-intellectual culture have a better chance at FAI?

This seems like essentially the same question as above.

Do Earths with less missionary rationalism have a better chance at FAI?

No. Missionary rationalists are a tiny fraction of world population who contribute most of FAI research and support.