[Northwest Outlaw]

I found this answer you gave on another thread. I think I understand what's going on, please correct me if I'm wrong. There is a relay switch between the lights and the switch, one each for the high and low circuits and the relay needs power feed and to be grounded.
My questions are probably basic, but like I said I'm new to all this.
A) What does the relay do? I'm assuming it's something similar to a fuse to keep the wires from getting hot?
B) What type and where would I get the relays needed?
C) does placement of the relay matter? I know the high and low wires both run through the dimmer switch inside the cab, or between the firewall plug and the radiator support. Would either of these locations work and is one better than the other?
D) Power source for the relay, should it come straight from the battery or come from the fuse block? I'm assuming it should be always powered, not keyed powered, since the headlights can be turned on without the key

I'll do more research as well.

Thanks again for all the help.