Do I need new hardware to mount this hub?

Use your existing factory lug bolts and caliper mounting hardware. The hub bolts directly to the factory knuckle—no new fasteners required.

Can I reuse the old tone ring or ABS sensor?

This assembly comes with the tone ring already integrated. Your existing ABS sensor threads into the back of the hub housing—no replacement needed there.

What if the hub spins freely but the wheel doesn't?

Check that the rotor is properly seated and the caliper isn't binding. A smooth-spinning hub with no resistance means the bearing is good. Noise or grinding points to the bearing itself.