Indeed, as you say, Decoherence explains why certain bases are special: when a system is in a pointer basis state, it does not continue entangling with environment (or, at least, does so minimally). When a spinning particle enters a Stern-Gerlach apparatus oriented in z-direction, spin-z is the pointer basis of the system during its time in the apparatus. A spin-up or spin-down particle does not entangle with the environment, but spin +x state would quickly entangle with environment, placing environment in a superposition and "branching" the total state vector of all the stuff in the universe.

Quantum Darwinism is just a refinement of this picture in which the "environment" interacting with the system is itself modeled a series of fragments (i.e. all the different photons that bounce off object). It turns out that the information about which pointer basis state the system is in (spin up or spin down) is redundantly encoded in each of these fragments. Hence, intercepting one photon that interacted with system and reveals "spin-up" (because the particle is in upper path) agrees with other photons that also bounce off object.

BUT, of course, due to linearity of unitary time evolution, there is another "branch" in which spin-down was the outcome of the measurement and everyone agrees on spin-down. This is exactly the Everett picture.

To take an example cited in the article, Einstein was so far up there that it’s nearly impossible for a non physicist to even understand what he was so good at — crude measures like high school grades or “IQ” barely scratch the surface of the skill that he was a genius at.

Now, perfect pitch does modestly correlate with musical ability, mathematicians are better than average at arithmetic, GMs do calculate more moves than the average shmo, and Einstein got much better than average grades (after all he was accepted at ETH). But that’s all, modest correlations.

There is such a thing as talent in music, mathematics, etc. but it isn’t something a psychologist standing outside these domains would ever be able to devise a test for.