You are correct on how a relay works, they use less current to switch the load.
Yes use a relay for headlights, most switches are only rated for 10A and old headlight switches have less than good contacts.
There is nothing wrong with incandescent headlights, but they do use a lot of power.
The reason some people, myself included have switched to LED is, they give off a much brighter white light with a huge power reduction. Also last forever.
I used 13 relays in my truck. One reason is you can run smaller wires to the switches and mount the relays in convenient spots. IF a relay dies its a quick plug and play deal.
This is a Sylvania Silver Star Headlight vs LED. LED is on the right.
My panel I made in my passenger fire wall.
Hope this helps a bit. Great truck by the way!!!
