I am no electrical expert but generally speaking you wont need additional wires ran to your light bar unless you want to control a couple of them seperately. Additionally you need to be aware of the total power draw you will be pulling. This will determine if your switch and/or relay for the lights is rated high enough to accomodate the extra lights. If you control them all from the same 2 wires you may need to go to a larger gauge of wire for better conductivity and less loss.
So the questions are:
What wattages are your 4 lights?
What current rating is the switch or relay you are using to energize them?
Be careful or you could burn up a switch that is rated too low. Consider installing a relay to provide the higher current needed to power 4 lights on one circuit safely.
Dont forget to be sure that the circuit has an appropriate fuse or circuit breaker in the loop.
Visit the Land Rover Beer Bar,"The Best Beer Bar X Far!"