Yes, you can change the Halogen bulb to an LED on a Path light. By changing the bulb, over time you will save energy and money. Before removing the old bulb, it is important to turn off the lights and allow them to cool. This is to prevent you getting burnt from the Halogen bulb. Once the bulb is cool, remove the existing bulb and place the new LED bulb in its place. After the bulb is secure in place, turn the power back on and see if the bulb is working properly. Before replacement, confirm that the new LED bulb uses the same voltage and bulb base as the halogen being replaced.
LED Path lights should be placed between 5 to 8 feet apart. This is a good distance for each light to illuminate a specific area without interfering with another light beam. If you are using solar paneled LED path lights, it is best to spread them about 7 to 8 feet apart. This will prevent them from interfering with the other light beams. While the distance does matter, how far apart each path light is from one another will also depend on the lumens of the light.