Lexicanum is good for checking names, dates, figures, locations and defining terms, but often poor on accuracy or only tells one 'version' in regards to narrative. I've also heard people claim that the admin is very much on having htings represented the way he sees it, rather than in the oft contradictory fashion of 40k.

I always saw Cypher's actions in the 13th (especially as the voice) as him being a 3rd faction - he wants Chaos stopped, but he also wants the High Lords and Adeptus Terra overthrown as only the Emperor can lead humanity.
As for his mysterious disappearing, I'd assumed it was linked to the Watchers in the Dark as they've displayed similar abilities (and disappeared El'Johnson).


Hive worlds aren't actually super populated. The highest recorded figure is 500 billion, but most given numbers are around 120 billion (while Istvaan III was 12 billion), which while a huge increase on current earth's population is being fitted into mountain sized cities.
There are stated to be around 35,000 Hive Worlds in the Imperium, which has approximately a billion worlds, probably more (based on there not being enough marines for one one every Imperial world). So Hives make up a tiny percentage of the population, around one four thousandth of a percent, and even taking into account a population of two hundred times that of an average world, they are still a tiny portion of galactic population.

There are a great many sources showing the Imperium isn't overly bad (though it is a huge cultural shift from our current world, so bad is subjective and relative). Dead Men Walking, the Cain series, Priests of Mars, Eisenhorn / Ravenor, the Fantasy Flight RPG books and numerous parts in many more all depict societies under direct Imperial rule where people hold steady jobs, go out at night with friends, go to bars, watch tv, go on dates, hope for promotions and so on. Hell, in Titanicus - set on a Forge World no less - one of the POV characters runs a toy shop!