Will this interfere with the factory bumper sensor?

No. The reinforcement bar is engineered to work around OEM sensor locations. Sensor cutouts remain clear and functional with this bar in place.

Do I need to remove the bumper to install this?

Removal depends on your preference. You can access mounting points with the bumper on, but full removal gives you cleaner access and faster installation. Either way works.

Should I paint this before or after installation?

Paint after installation if you want a factory match. That way you avoid paint chips during fitment. If you paint first, use light masking tape at mounting points to protect the finish.