-Yes, you can buy UV lights that plug into the molex connectors from the PSU.
-No, there arent any other connectors on the mobo for extra LEDs. To add more LEDs you would need a molex pass-through connector, some resistors, and will require soldering. (Unless you want to be old fashioned and use electrical tape)
-Yes, additional fans connect to the PSU like the UV light. They use a molex pass-through connector. Although, some fans can connect to the motherboard. These use 3-4 pin connectors.
-Most fans use 12v. The ones Ive seen anyways, and if you did plug it up, it would only use the power needed.
-All you need to add more fans is...well more fans. What you would need for a UV light...is a UV light, and for LEDs, wire, soldering iron/solder, and resistors. Im not sure what kind of wire or resistors you would need, but Im sure someone here knows.