Spin Polarized Current: Magnetic Moment & Interaction

[lufc88]

How come normal current has a magnetic moment if 50% of electrons have spin up and 50% have spin down. Is it because they have to be in pairs?
Would a wire of current with electrons all polarized up attract a wire next to it with electrons all polarized down?

Extra question
How come superconductors have no B field by the way?

 

[Nessdude14]

The magnetic field caused by a current isn't a consequence of electron spin. Any electrically charged particle that is moving will produce a magnetic field.

 

[lufc88]

Sorry ignore the first question so again why does a superconductor have no magnetic field inside of it if electrically charged particles are moving.