How can a trade route be destroyed? Is there even a method?
At one time you could click on a trade route in that screen, then click on the Delete button. There is no delete button now. I'm not sure now if there ever was one in GalCiv4. I tried everything I could think of without being able to delete a trade route.
I would prefer if there was an easier to tell which civ is available to trade with at a glance, right now I have to go trough
Not all Capstone techs are marked as such, I think Manufacturing Stimulus is the only denoted.
Click on the icon in the yellow circle. If the icon in the yellow box exists, you can trade with them. You can scroll that list to see all the races you have met.
I've done some testing and found that the space "creatures" ignore probes, attack and destroy weak military ships and colony ships. They stay away from strong military ships. I had a freighter go through a group of sentinels without being destroyed. The sentinels just used ranged attack against the freighter, which didn't do enough damage to destroy it before it got away. I haven't tested anything else.
Also, the space monsters lay an egg in the debris of destroyed ship, which then produces a new space monster. It all happens in an instant, so all you see is a ship get destroyed and a space monster appear in its place.
Before Supernova, pirates would attack colonies and conquer them. They don't do that now. I wonder if that has been changed on purpose or if the new siege procedure won't let a single pirate ship attack a planet because it is enough to take a planet.
None of them is much of a problem now, mainly because they never form fleets on their own.