The house's exact location is never confirmed. It's described as a Victorian-era townhouse that appears to have been uprooted from its neighbours and dropped in a country valley. Its stones are still sooty, which suggests it originally stood in a large city like London, or perhaps a smaller industrial centre. It is variously described as three or four miles from the nearest neighbour and from the closest village; it seems to be four miles by road, at any rate.
The house itself is four floors, including the attic. A floor plan used to be available online as part of Howard's Dungeons and Dragons article on including Cabal in 4th edition adventures (this document disappeared from the Wizards website in the summer of 2014, and doesn't seem to be hosted elsewhere).
The basement is intentionally boring and disused-looking. It has some storage, the boiler for the house, and a well-disguised entrance to Cabal's secret laboratory. The secret lab is forty feet square and ten feet high; it contains workbenches, shelving with specimens, his arcane library, and an operating table/postmortem slab. It's lit with fluorescent lights.
The ground floor includes a parlour and kitchen. The remaining two floors are bedrooms and a water closet, including hte master bedroom where Cabal sleeps.
The attic holds Cabal's other laboratory, where he does much of his work.
The house, like the setting in general, uses a bewildering array of heating and lighting technologies. It is lit with candles, oil lamps, fluorescent tubes, and lightbulbs. Water is heated with an oil-fired boiler, the rooms are heated with coal fireplaces, and the stories also refer to a furnace "down in the cellar" in which Cabal disposes of bodies; this last may not actually be at the house, but it seems likely.
The house has a front and back garden. The front garden, at least, is home to tiny carnivorous and malicious fairies who serve as a front line of defence against intruders and salesmen. There is a woodshed which sometimes houses Cabal's larger and more ambulatory experiments. The garden wall contains sigils of warding.
The secret laboratory also holds, beneath the floor, a tank in which the body of a young woman is suspended; it is heavily implied in the stories that this young woman is the reason for Cabal's quest for perfect resurrection.