Yes magnetic fields and spin are expected to deform neutron stars slightly.

I think they'd probably be spherical. They are super dense, so there's not much space between the atoms. That's what makes them dense and heavy. So imagine a bag of popcorn with all the little popcorn bits popping out at weird spots. Then take it and crush it in your hands to make a circle. It's still the same mass (weight), but now it's more dense since it's smaller. And as you squeeze the popcorn it sticks out less. That's mostly because you're squeezing the popcorn, and applying a force to drag things to the center. There's still gravity inside a star, so that's what gravity is doing. And the more dense it is, the more tightly packed, and so the gravity will keep it tightly together. So that's why I think it'd be spherical.