Do I need to remove the radiator support or drill into the frame to install this?

No. This grille uses the factory mounting holes in your existing grille opening. Unbolt the old grille, bolt in the new one—no drilling, no cutting.

Can I paint this, or does it need primer first?

It comes in gloss black ready to go. If you want a different color, sand with 120–150 grit, apply automotive primer, then your topcoat. Skip the primer step if black stays your choice.

Will this affect airflow to my radiator?

Vertical slat grilles maintain full front-end breathing. Air flows through the spaces between slats the same way it did through your factory opening—cooling performance stays unchanged.