2001 F-250 SC dome light

[trogmaster]

Current dome light is just 2 map lights. Only lighting is the 2 red courtesy lights in the doors. Would like to install an overhead light.

Can I use the existing dome light or purchase another w/the center light?
Also, does the wiring from the courtesy/3rd brake light above the back window come thru the headliner so I can tap into the hot and ground?

thanks