Turrets not firing was probably my fault. I have no idea how that happened and even less of an idea on how I managed to fix it (fix not merged yet). I just changed coords to 3d and suddenly turrets started firing.
Someone suggested disabling the limits on electric engines having negative epower. In the PR with the above fix, I removed the requirement that the engine would have to be a plasma engine to produce power. That may (or may not) enable engines producing power, though not electric engines doing it - those have to be hardcoded to be skipped in power production stage.
Also in the same PR I tried to generalize reactors to any fuel rather than hardcoded plutonium. The new reactors will be basically fuel containers that can consume stored fuel to generate electric power and scale their production to power needs (stop consuming fuel when batteries are full). This may be useful for any warp engines, though they will still need to consume something.