If the sphere is air-tight (which it would be) atmospheric pressure would be the same everywhere inside.
Gravity would be highest at the equator, and gradually reducing as one moves from the equator to the poles, at which point it would be zero.
But the artist should double check his figures for diameter vs. rotation speed; a sphere 3.53km in diameter rotating at 1.9rpm will have an effective gravity of slightly over 7g at its equator!
A rotation speed of 0.7rpm is fast enough for a sphere of this size.
Here's the tool I use for work like this: www.artificial-gravity.com/sw/…