Do I need special tools to install this hub?

Basic hand tools and a socket set will get you through most of it. You'll need a jack and jack stands to safely lift the vehicle and remove the wheel. An impact wrench speeds things up, but it's not required.

Can I reuse the existing wheel bolts and studs?

If your bolts and studs are in good condition with no stripped threads or corrosion, you can reuse them. Inspect them during install and replace any that look worn or damaged.

What if the hub won't seat all the way onto the axle?

Clean the axle shaft and the hub bore thoroughly—rust or debris prevents a flush fit. Use a wire brush or sandpaper to remove corrosion. A light amount of penetrating oil can help. Never force it; check alignment before tightening bolts.