for the gauges,

red = switch live,
yellow = perminent live
black = earth
orange = light switch , so they light up with your lights,
green = what ever sensor

stereo, much the same as above,
blue will be remote to amplifyer, blue/white will be feed for the power arial (you dont have one so leave that out)

head light should come with plug in adaptors.

safechav will be able to help you more, or maybe some one with twin headlights

good luck