[rjsimmon]

How much does the core move per day compared to the 24 hour rotation of the surface?

Just a fraction of a second faster than the outer crust.

Core spin

Although, there is an alternate theory that the core spins in the opposite direction

Opposite spin

Though I would question that on the basis of hydrodyamic flow and tidal eddies that would seem to want to cancel out that opposite spin.

[Mr. K]

wow!
and that fraction of a second is enough to generate a magnetic field strong enough to deflect solar particles?