Will this wing interfere with my trunk lid or hatch opening?

The RS-spec profile is designed to clear a fully open hatch. Verify your hatch swing clearance by opening it fully against the back wall before final installation; high-mount spoilers like this one can contact the panel edge on some setups with aftermarket hinges or modified latches.

What mounting hardware comes with this wing?

The wing ships as the FRP assembly only. Source fasteners that match your vehicle's factory hatch attachment holes and torque them per your service manual to ensure stability at highway speeds.

Do I need to seal or waterproof the mounting holes once installed?

Seal all fastener holes with a weatherproof sealant after installation to prevent water from entering the hatch cavity. FRP itself doesn't require ongoing sealing, but the joint between the wing base and your panel will benefit from a bead of automotive trim sealant.