Do I need to remove the bumper to install this?

No. This hitch bolts to factory mounting points underneath the bumper without removing it. You'll have access from underneath the vehicle.

What size ball and coupler does this use?

This is a 1.25" Class II receiver. Any standard 1.25" ball mount, coupler, or hitch accessory will fit. Your trailer coupler size determines the ball size you'll need separately.

Is any painting or prep required before installation?

The hitch arrives ready to install. If you want to refinish any exposed metal or match your bumper, that's optional — it won't affect function.