Do I need new fasteners to install these, or can I reuse the originals?

Reuse your original mounting bolts and fasteners. Just clean them before installation and tighten to factory spec per your vehicle's service manual.

What's the difference between a hub assembly and replacing individual bearings?

This is a complete sealed unit — bearings, races, and seals come together as one piece. You swap the whole assembly instead of pressing individual bearings. Faster, fewer tools, no need for a shop press.

Do these work with aftermarket wheels or just stock sizes?

These bolt to your existing suspension. They work with any wheel and tire combination that fits your vehicle's factory specifications.