Do I need to replace both sides or can I just do one?

You can replace one hub, but wear is typically even across the front axle. Replacing both keeps your suspension balanced and prevents pulling or vibration down the road.

What hardware do I need to bolt this in?

This assembly does not include mounting bolts or fasteners. You'll need the fasteners from your vehicle's original hub — they reuse cleanly with this unit. Your service manual lists the exact torque spec.

Can I reuse my old wheel speed sensor?

Depends on condition. If your ABS sensor is clean and the wiring is intact, transfer it to the new hub. If it's corroded or damaged, replace it at the same time — sensor failure is common alongside bearing wear.