[quote=@Vor]
I'm a sucker for in-depth RP's and this looks mighty interesting, however I'm a complete WH40K noob (only played the Dawn of War games + casual reading of random articles on the Lexicanum). Think I'll manage to fit or does this require too much knowledge of the setting to successfully pull off? Really, my biggest problem is that I find it hard to get into the head of characters serving the Imperium; like, how does religion/fanaticism factor into their day to day lives, what's considered to be stepping over the line in terms of morality, that sorta stuff. 

[/quote]

Imperial citizens are absolutely and utterly indoctrinated by the Imperial Cult, the unshakable faith that the God-Emperor watches over all. This is of course heavily abused by everyone in charge to convince the billions upon billions of masses to slave away in the name of progress and safety. Most citizens are heavily superstitious and xenophobic but generally unaware of the exact nature of the forces arrayed against them. Chaos, especially, is all hushed up and hidden from the general citizenry. 

Arbites are the ones to ensure all of that nonsense happens without too much crime. They're tough and unforgiving bastards who err on the side of summary execution. Only important officials have a right to a trial. That's the general mindset. It's all for the good of the Imperium and the glory of the Emperor, not for the people.