Do I need to buy the left side headlight too, or can I replace just the right?

You can replace just the right side. This is a single assembly — order the left separately if both need replacement.

Will this bolt straight into the factory mounting points?

Yes. This assembly uses the same mounting points as the OEM headlight — no drilling, no adapters, no custom brackets needed.

Does the bulb come installed?

The assembly ships without a bulb installed. You'll need to source the correct bulb type for your truck and install it before operation.