1) I've created orbital habitats with 100 sorium harvesters each, and moved them in orbit of a super jovian with around 85m units of sorium. Is there any way to see the fuel that they created? And while I'm on this note, do the orbital habitats need fuel storage themselves in order to produce fuel? I've noticed that the amount of sorium decreases, but I can't see the fuel, is it lost to oblivion?
Fuel gathered from orbital refineries are placed directly into fuel storage. They do require fuel storage to store the fuel.
2) Slightly related, but I created a new orbital habitat with actual fuel storage in case that was my issue, but I can't make it unload it's fuel. Currently it's in orbit of Earth, and holding millions of gallons of fuel hostage. How do I make it release it's fuel before tugging it to a sorium source?
You have to tag the design as a tanker in the ship design window, the top right corcer, for it to get those orders.
3) I've been contemplating making extensive orbital habitats loaded with sensors, plasma carronades, CIWS's, and perhaps some missile launchers, then dropping it off at strategic jump points to catch enemy ships when they enter the system. Is this at all a plausible idea? Or would this just jeopardize what would inevitably be a massive investment of resources?
That is currently not plausible, but will be in the next version.
4) As for terraforming, my current method is several large orbital habitats that get tugged around to the location I want them to terraform. The only problem is, this takes a lot of time to drag the massive habitats into position. Would I be better designing smaller habitats and mass producing them, or perhaps designing some self-propelled terraforming ships to have a more flexible option?
All depends on preference. Larger single units are most cost effective, but they do take longer o get into position.