Do these use the stock mounting holes, or do I need to drill?

They mount directly to factory attachment points — no drilling. Line them up and bolt them down.

Will these covers fit over my existing handles, or do I remove the old ones?

These are designed as direct replacements. Remove the factory covers first, then install these in their place.

What's the difference between textured and gloss black finishes?

Textured hides dust, fingerprints, and water spots much better. Gloss shows every mark but looks shinier fresh. Textured holds its appearance longer between washes.