Will this interfere with my trunk or hood closure?

No. This is a front bumper lip, not a trunk or hood component. It mounts low on the front fascia and does not affect rear panel clearance. Verify mounting hole alignment with your bumper before final installation.

Should I use adhesive or drill through the bumper to mount this?

The mounting method depends on your bumper's existing hardware. Most installations use the factory bolt holes in your front bumper. If holes are not pre-drilled, determine your preferred method (drilling vs. adhesive) and prep accordingly before mounting the lip.

Will this stay stable at highway speeds?

Yes. A proper installation using your bumper's mounting points ensures secure attachment. Confirm all fasteners are tight before driving, and periodically check them after highway runs to maintain full stability.