One of the things that proponents of kinetic energy weapons from orbit do not often discuss is that hypersonic reentry heats objects so much they will disintegrate unless special conditions are met. We see this happen with almost all meteors. Studies of how tungsten rods would melt have shown the "rods from god" scenario is much harder to pull off than one would guess. Recall, these same forces are what destroyed Space Shuttle Columbia, and that had heat shield covering all but a tiny portion that was damaged at launch. I don't know if CIG has sufficient physics in game to make kinetic weapons possible, but even given they did you would have the thermal issue to look after. Simply dropping full fuel tanks on someone could be a better option.
This is true, but they have worked out the physics for the USAF study, and that does work. That was the origin of the 20 ft by 1 ft tungston telephone pole. That was the effective size and shape. The problem with kinetic strikes is they become very expensive ways of executing what amounts to a surgical strike, with an impact zone of just a few square meters, but very deep. The major expense is lifting the kinetic bundles into orbit. Right now that's not cost effective vs flying a plane nearby and executing a stand-off strike.
But all this assumes that your target is on Earth or another thick atmospheric body starting from fairly low orbit. Actually what you would do is use Stellar gravity, you can achieve far higher velocities by starting the drop from a stellar intersection orbit, like for example starting out near Jupiter's orbit or so. But it's still dang expensive to get out there.
Still though, they would be fairly effective on a moon or planet without a thick atmosphere. The idea would be to soften the target by cracking it open and exposing the interior to the vacuum, even if it was buried.