Do I need a special tool to press the old bearing out?

You'll want a bearing puller or access to a shop press. If you don't have one, most independent shops will press and inspect for under $50—saves you buying tools for a one-time job.

Will this work with my ABS brake system?

Yes. The ABS sensor ring is integrated into the hub assembly, so it communicates with your factory ABS module without modification or additional wiring.

Do these come with the castle nut and cotter pin?

Hardware is not included with this assembly. You'll reuse the castle nut from your old hub or source a new one—it's a common fastener at any hardware store.