Overall, interesting changes and I think a step in the right direction without changing the game too radically.
The Skirantra nerf and other cap ship buffs should add some variety to the beginning of games. Halcyon looks pretty good right now.
The Hoshiko buff shores up late game TEC fleets.
I'm not sure how valuable Subverters will be after the nerf. I suppose they will still have their uses, but because they are kind of expensive and tend to die quickly when being used, players may just buy more fighting ships rather than the "suicidal" subverters.
The Kostura not being able to hurt ships is a good change. Kostura should still be plenty valuable for damaging structures and opening up phase gates.
Novalith Trade Disruption sounds very powerful depending on how long it lasts. I suppose I can see how a disaster on the planet could affect orbital trade, but I'm kind of on the fence here. Probably outside of the scope of the game engine, but it would be really cool if the Novalith just turned planets bigger than asteroids into Volcanics. (I'm assuming that a huge shell with enough velocity to travel between solar systems in a short amount of time would probably set off serious tectonics and crack the planet's crust.)
Advent Super Canon still needs some love.
If TEC Cannon disrupts trade, why not allow the Advent Cannon to steal a percentage of trade income for a while. Kind of like a long range Sova affect, but the amount of trade stolen would be the same as the amount of culture temporarily lost. This would have the dual effect of making the Advent Super Cannon more viable, as well as contributing to the Advent late game economy.