Do I need to buy bulbs separately?

Yes. The assembly arrives empty—you'll need to source the correct halogen bulb separately and install it into the chamber.

Will this bolt straight onto my vehicle without modification?

Yes. It uses factory mounting points, so it bolts in the same way your original did. The electrical connector is OEM-style plug-and-play.

What if I only need one side replaced?

This is a single right-side unit. If your left side is still good, you only need this one. Order a left-side assembly separately if both need replacement.