Do these require any wiring changes or harness adapters?

No. These bolt directly into your factory mounting points and plug into your existing electrical connectors. If your original headlights work, these will work without modification.

Will I need new bulbs, or do these come with them?

Bulbs are not included. Your current bulbs transfer directly into these housings. If you're upgrading to LED or HID at the same time, make sure your bulb choice is compatible with the socket type in these units.

Can I paint or refinish the black housing if I want a different color?

The housing is hard panel construction and can accept paint, but you'll need to mask off the clear corner lenses carefully. Test on a small area first to confirm adhesion and curing. Standard automotive prep and paint process applies.