Will this interfere with the trunk seal or undercarriage at speed?

No. This lip mounts to the lower bumper fascia well below the trunk line and is designed for street use. At highway speeds, ground clearance remains adequate for normal driving on paved roads.

Does the brake light cutout align with factory lights?

This is a front lip air dam—no brake light cutouts are present. It sits below the front bumper and does not interface with any lighting components.

Should I use adhesive or bolt this down?

Bolt-on mounting is recommended. This piece uses the existing lower fascia attachment points, so you'll need standard fasteners appropriate for your bumper assembly. Adhesive alone is not sufficient for sustained highway use.