All very interesting! I am interested as to why the night lords don't follow a good, read they as a whole they don't have curroption or mutations in them.
The Night Lords never really liked psyker even when they were at the emperor service...and unlike the Death Guard, they never had any personnality that inducted them into institutionnal sorcery, and Sevatar, one of their most popular 1st Captains, didn't liked mutation particularly.
After the heresy, the Night Lord were one of the legion that didn't flee straight to the Eye of the Terror. They mostly remained in imperial space and waged a war of hit and run against the imperium until their Primarch died.
After that, the legion broke, some ran to the eye, other stayed in normal space. But don't make mistake, they are corrupted, it's just that their corruption is more anarchic than in the others legions. Where chaos cult is institutionalized, like the Black Legion or the Word Bearers.
Before even being renegade, most of the Marines of the Night Lords were ancient youth criminal, and their terran brethrens where from human stock that lived in huge subterranean prison city.
All in all they are individualist and quite cynical and ADB has made them AWESOME !!!