Do these bolt straight to my truck without modification?

Yes. These mount at factory connection points with no drilling or cutting required. A straightforward swap.

Can I run the halo rings on their own, separate from the main headlights?

The halo rings have independent wiring, so you can wire them to run as accent lighting or keep them tied to your low-beam circuit. Your preference on setup.

Will these need bulb replacements or are the LEDs permanent?

The LED halos are solid-state and designed for the life of the fixture. Verify bulb type and availability for the projector beam element when you receive them.