Hopefully
@Maugan Ra won't mind me stepping in and doing a bunch of lore posts, since I have (almost) all the Dark Heresy 1E PDFs.
A Basic Primer to the Calixis Sector
Origins
The Calixis Sector is in the northwestern corner of Segmentum Obscurus, resting on the very edge of the Imperium. To its spinward, the Koronus Expanse, where Rogue Traders seek to expand the Emperor's domain further. To its rimward, the infamous Halo Stars. Coreward is the Ixaniad Sector. To trailing, the dangerous Fydae Great Cloud, and the Scarus Sector (the setting of the Eisenhorn and Ravenor novels).
Calixis has a dark and ominous history. It was first documented in M35 as the Calyx Expanse by the legendary Rogue Trader Solomon Haarlock, calling it a "chalice of great and ancient wickedness" that would only be purchased for the Imperium with a "great effusion of blood." At the time, it was ruled by the Yu'vath, a xenos species with an appropriately dark nature.
In M39, the Imperium launched a campaign to conquer the Calyx Expanse as part of a Crusade under Lord Militant Angevin. It would be spearheaded under a General Drusus. There are a multitude of stories about Drusus, his origins, his feats, and deeds, but here are the core facts. Drusus was an inspired leader who led the crusade to many great successes. Then, while resting on the world of Maccabeus Quintus, he became a Saint. Again, there are many conflicting tales about what happened, but this much is clear: an assassin nearly killed Drusus, but the God-Emperor's power destroyed them, and resurrected Drusus.
Saint Drusus would go on to exterminate the Yu'vath, complete the conquest of the Calixis Sector, and become the first Sector Lord, until his death (for good) in 417.M39. He was in many ways the founding father of the Calixis Sector, and Drususian worship is a core pillar of the Calixis Ecclesiarchy.
Sub-Sectors: Golgenna Reach, Malfian Sub-Sector, Drusus Marches, Adrantis Nebula, Hazeroth Abyss, Josian Reach, Markayn Marches, The Periphery.
Sector Capital: Scintilla, Golgenna Reach.
Sector Governor: Marius Hax. Lord Hax is from an ancient Terran-descended family in the heart of Segmentum Solar, appointed as Lord Sector by the High Lords of Terra approximately 250 years ago (accounting for the time shift into M42), ruling Calixis from the Lucid Palace on Scintilla (of which he is also the official planetary governor). Lord Hax is an extremely grave and austure man, with an absolute conviction that order and obedient rule are essential to humanity's survival.
At the same time, he is a surprisingly even-handed man, who values and listens to good advisers. Hax rules in an "hands-off, big picture" fashion, generally ignoring events on individual planets, but only sleeping four hours a night and reviewing daily economical and fiscal reports in great detail. His priorities are the tithe, quashing rogue psykers and rebellions, and upholding the authority of the Imperium.
In short, not bad as Sector Lords go, except Marius Hax has been slowly descending into paranoia and tyranny. He has enacted various measures to increase his control over the Calixis Sector, including the notorious Chaliced Commissariat (a highly loathed formation modeled off the Commissariat to oversee PDF units). This state of mind is not of his own making, but engineered and encouraged by conspiracies within the Lucid Court. Needless to say the birth of the Cicatrix Maledictum is unlikely to improve the situation.
Major Planets
Scintilla: The capital world of the Calixis Sector, Scintilla is a hive world of 25 billion, the largest population in the Sector. Dominated by the Hives of Sibellus and Tarsus (with Ambulon and Gunmetal City as runner-ups), Scintilla is the economic, political, and religious heart of Calixis. As all of our options start here, I'll detail the planet further in a later post.
Malfi: The capital of the eponmyous sub-sector, Malfi is a semi-tropical hiveworld with a massive grudge against Scintilla for taking what the population believes to be Malfi's rightful place as sector capital. It is also notorious for being an absurd hotbed of intrigues. Every act and motion of Malfian life is about dissemblance and intrigue. Malfi's elaborate, layered culture of falsehood and deceit makes it laughably easy for numerous sects and cults to recruit and conceal themselves.
Iocanthus: A lawless world dominated by and their huge armies, clashing across the planet's forests, jungles, and plains. Iocanthus' sole meaningful export is also what makes it so important: it's one of the few places where Ghostflower pollen (a key ingredient in the combat drugs used by Imperial Guard penal legions) can grow. Because Ghostfire cannot be cultivated normally, the warlords (styled 'vai', meaning prince) and their armies are constantly on the move looking for new patches to harvest and fighting for control. Every five years, the warlords turn over their hauls to an Administratum task force in exchange for weapons, clean water, and other supplies. The one that provides the most Ghostfire pollen is named 'Vervai' ('King') and Planetary Governor.
Sepheris Secundus: The epitome of feudal worlds. Everyone born on the planet has a master to whom they pay nine-tenths of what they produce, starting from the billions of serfs, moving up the chain to the barons, the monarch, and of course the Imperium. Tradition and force maintains an antiquated system dependent on serfs living in city-size mines, hacking away at ore faces with basic, primitive hand tools. In short, the planet would be a joke if it weren't for the amazingly vast mineral weath underground, enough to make it key to the Calixis Sector's economy.