I'm using Denso IK22 Iridium's but hey will not really suit your stock application. Not sure about those leads, haven't had anything to do with them, I am using NGK leads currently, however, Cmapion and Bosch should be fine.
#3 looks sooty, possibly combustion gases, may not have been seated correctly.
#4 looks like the spark plug tube was loose.
This is a handy little chart, however it is aimed solely at the electrode end.
If the Hi-beam light is working there is a good chance the stalk is fine since you have changed it with the same issues. You could use a test light to check if there is power at the plug where the globe connects. If there is no power, then there is the possibility of wiring damage. There is also 2 filaments in the low beam globes, one is on for low beam and the other is for the high beam, they should never both be on at once.