Do I need to remove the original headlights to install these?

Yes. The OEM units come out first, then these bolt in at the same factory points. It's a straightforward swap with basic hand tools and takes about 30 minutes per side.

Will the black housing affect light output?

The internal reflectors and lens elements are designed to function at full brightness despite the darkened housing. You'll get the same illumination as stock, just with a blacked-out appearance.

Are bulbs included, or do I need to transfer mine from the original headlights?

Transfer your existing bulbs from the OEM units. The assemblies are designed to accept your current bulb type without modification.