1) Any evidence Bosch had family that came from the GTI war (silent threat) (who made the Hades ship)?
None.
The only conncetion Bosh has in canon to Silent Threat is that in one of the monologues he mentiones having fought the "rebels" of the Great War... which might also mean the Hammer of Light....
2) Sathanas suck in Nebula gasses for some reason. Nuked Capella not because of us, but because they wanted baby nebula to feed on. Or: 3
a) The first time we saw Sathanas was in Nebula. Created Nebula from Capella. Took many Sathanas to supernova sun, so designed to do so. Important enough to loose the lives of crew and materials of entire Sathanas ships from attempt.
We don't actually know if the Shivans value their ships and crew, or that a Sathanas is really an important kind of ship (we know the Lucifer is, in canon); if they as the canon suggests are some sort Gestalt entity (Hive Mind, Distributed Intelligence Network or similar) it might just be that a the loss of single ship might not register as significant (again, the Lucifer is the exception to the rule). The existence of the entire GTVA might *just* inside their range of perception...
We do have evidence that Shivans mine Nebulae but then we don't know for what exaclty - a normal supernova remnant, which the Nebula is suggested to be, would consist of a variety of elements (e.g. the GTVA is able to mine large quanteties of Argon from the Nebula)
That being said it is not exaclty clear if the destruction of Capella actually followed the rules of a supernova and that the resulting remnant nebula would be similar, e.g. the "sun of Capella" doesn't go through the stages of stellar age that would come before the collapse of the star into itself as part of the nova. You can mark some of it up to artistic license, I mean they ignored Capella being a binary star system, but considering some of the stages of stellar evolution are responsible for the creation of heavier elements that kind of accelleration might not yield the same results....
... so take it wherever you want.
4) Jumping to a location in subspace is instantaneous. However when attacking Lucifer, it took time. Jumping causes you to age faster.
a) Ancients used subspace. What if a group of them entered subspace and never left yet. Subspace engine on a space station perhaps? To stall for time, or to study how to defeat shivans (besides the no shields thing)
There are 5 canon rules about subspace jumps:
1. A subspace jump is point to point along a single fixed trajectory.
2. The trajectory of a jump cannot be altered once engaged.
3. There is a delay between entering subspace and exiting subspace at your destination.
4. Travel from one system to next requires use of jump node.
5. A subspace jump requires the jumping ship to expend a large ammount of energy.
The final mission of Freespace 1 also suggests that when in Subspace, the jumping ship is itself not moving but the space in which it travels through subspace is (or at least that is my explaination so the scenario makes sense).
However considering the "rule" that "the most widely used version of technology is often the safest version of that technology" leaves the door open for many other, dangerous ways to harness the existence of subspace. Including jumps that violate each of the four rules but that have side-effects (e.g. a jump drive that doesn't draw energy from the ship that jumps but from the area it is jumping to; allowing for rapid jumps but creating an implosion every time you do)
5) Why not approve the Hades project? Nothings wrong with combining best technology from each species to defeat enemy. GTI believed in it strong enough to defect to see it through. There had to be more 'technology' than just aesthetics added into a Destroyer class shell. Did we ever learn of any technologies taken from Shivans and used for our benefit?
There is no canonical explaination what the Hades was actually about...
ST:R expanded it, making the Hades a plattform for orbital bombardment; which at the time it was unveiled no longer had a purpose as the alliance held through the end of the Great War. The suggestion in ST:R is that GTI wanted to use the Hades instead of allowing it to be dismantled as a good-will gesture towards the Vasudans (or quitely be sweept under the rug because its existence would be a burden on bilateral relations).
There is another problem however, as we learn in Freespace 2 Shivans communicate via "quantum waves" and Freespace 1's species description gives the impression that the Shivans are at least partially merging biology and technology. This poses a problem with understanding every piece of Shivan technology that we don't understand the purpose of (so unlike a gun, shields, sensors or a fighter), as they might be build with a way of interfacing in mind that the GTVA might not be able to replicate (e.g. what if the communication via "quantum waves" means that Shivans network with technology without the various layers of interface we take for granted because we are unable to manipulate magnetic fields or electric currents - a Shivan computer may be just be an inert, black box to us)
The whole "quantum waves"-buiness has even more implications to the kind of reality the Shivans are living in, e.g. does the Uncertainity Principle apply to them? If No, what is the effect of that going up through the scales (atmoic, every-day, cosmic)...
... aaaand here is the rabbit hole....
EDIT: speaking of black boxes
Terran Engineer: Our ancestors found this in cockpit of a shivan ship. We think its a navigational super-computer, but so far had no way to access it.
Shivan: It's what you would call a music box. See, you use this n-dimensinal manifold here to make it emit atmospheric vibrations across the range of audible sound.
Terran Supervisor:
