Just a quick selection of WH40K quotes with commentary while I get a few things sorted out:
FTL speed
For example, a 100 light year jump will seem to take from 234 to 934 hours to a spaceship's crew, but between 3 days and 3 weeks will have passed in real space. These times do not include journey times out to and from jump points on the edge of the star systems. It takes from days to weeks of travel at sub-light speeds to reach a drop from the spaceship's starting planet, and a similar time to re-enter the destination system.The Imperium is approximately 75 thousand light years from edge to edge. A journey of this length would take between 75 and 300 days in warp time, and between 6 years and 40 years real time.
Those figures translate to 1,875-12,500
c for 75,000 light years, 1733-12175
c for 100 light years.
"Apparent" speed aboard ship is much faster but not very consistent.
5,000 light years would be the normal maximum jump, but longer jumps have been made.
Individual jumps are generally no more than 5,000 light years. Fairly straightforward.
Perceived journey time is 1-4 days per thousand light years, equivalent to 1-6 months of real time. Even so, a journey from one edge of the galaxy to the other would take between 85 and 510 months of real time.
This gives 2,000-12,000
c. Looks, actually, remarkably consistent so far, although the variability in the dilation is pretty large. The Imperial Guard book, though, muddles things:
Ten thousand light years can be traversed within 10-40 days by warp-capable spacecraft. By the
time ships have been moved into position, munitions collected and troops assembled, the response
time over this distance is in the order of between 30 and 120 days, typically about 75 days.
This has been given before
as the apparent time elapsed on the ship. Now we've been given 90,000-365,000
c in the context of
response time.
Ground warfare
In addition to their support and technical personnel, a Chapter contains tens of thousands of Marines (Note that after the Heresy new Chapters were formed with far smaller complements so that no Commanders would ever wield the same power as Horus).
High end of current chapter size: Tens of thousands of active Marines plus support personnel.
The Legiones Astartes is known always as the Space Marine, it comprises 1000 independent
fighting units called Chapters, each of roughly 1000 fighting troops.
Low end: ~1,000 space marines per chapter.
There's also a list of space marine abilities. Unfortunately, it doesn't seem to include hyper movement speed, new kinds of muscular tissue, or reflex speed increases. All in all, I gather the impression that Space Marines are not particularly consistently described.
On the hive-world of Thranx over a million warriors died in a single day on the killing fields of Perdagor.
Someone in Games Workshop reads Alan Dean Foster.
Fleets
The Space Commander has direct command of a portion of the Segmentum's warfleet. A typical
command comprises about 50 interstellar ships, although the number would obviously vary
depending upon the needs of the sector.
A typical sector fleet has 50 interstellar warships. Straightforward enough. The whole of the Imperium fleet is "many thousands," with nothing more specific anywhere I could find.
The Imperial fleets number many thousands of ships, the majority of which are at least a thousand years old. Some are as old as the Imperium itself, a full ten thousand years. A very few claim a pre-Imperial origin. It is difficult for those born under the claustrophobic sky of a planet to appreciate the great dignity which is inherent in all old spacecraft. The spaceships of the Imperium are vast constructions that take many decades to build.
Average service life is longer than that of a Miranda or even a Klingon battlecruiser.
On the flip side, the Imperium isn't producing ships very quickly.
The living areas of a spaceship contain the thousands, often tens of thousands, of men that serve
aboard.
Thousands to tens of thousands of operating crew. Hundreds of thousands on maint duties, by the way.
Most of the galaxy remains unexplored.
A reiteration of the whole "space is big" theme. Warhammer's galaxy is much like ours.
Storms are constantly forming and dying down, at any time at least 10% of the galaxy's solar systems will be inaccessible because of storms.
On average, 10% of systems are inaccessible to FTL WH40K ships. Interesting fact.
One giant craft span out of control and crashed into a hab-unit, killing a hundred thousand people.
(This is from the Horus Heresy, by the way.)
Not a strange death count for a falling ship.
More importantly, however:
The great Sky Fortress bore Rogal Dorn and the remnants of the Imperial Fists to the inner palace. The loyal old general was determined to stand and die with his Emperor in the final hour. The Sky Fortress raced away from the palace in a desperate attempt to reach Jhagatai Khan and return him to the palace. It was destroyed by a blaze of fire fron the Death ́s Heads Titan Legions. Even in death its commander wrought havoc on the enemy, bringing the crippled vehicle down into the entre of the Chaos Horde. It seemed as if a new sun was born on Earth as the plasma reactor exploded, blasting out a crater three kilometres across. Those within the palace knew they were cut off; now they were truly alone. Only a miracle could save them.
Sky Fortress reactor exploding = 3 km crater on Earth.
Macharius' strategy of sudden and decisive attack was working better than could have been imagined. A hundred worlds fell to him in one year, three hundred the next, and in the third year of the campaign nearly seven hundred planets were taken by the combined forces of the fleets of the Segmentum Solar and the Imperial Guard.
The Imperial Guard's idea of a lightning-swift campaign. Not bad, actually.