Will these bolt directly into my T680 without any modification?

Yes. These mount at the factory anchor points with no drilling, cutting, or frame work needed. Bolt straight in using existing holes.

Do I need to source bulbs separately, or do these come with them?

The assembly itself is included. Confirm bulb type and sourcing with the product spec sheet or contact support before ordering if bulbs are critical to your purchase.

What's the difference between these projector lights and standard reflector headlights?

Projector optics focus light into a tighter, more controlled beam with a sharper cutoff line. Reflector designs spread light more broadly. Projectors typically offer better visibility and a more modern appearance on the road.