That would be a biggie on my list as well and it only improves the gameplay. I'm sure we will see something like that, either in the base game or in one of the many expansion Sega will have them churn out.

Static defences would be interesting (by which I mean - awesome!) but I doubt Amplitude will have time to implement them before the end of early access. I mean, that would require new models, textures, sound assets and AI. Lot's of work.

I'm not too keen on small ships working as militia. Militia makes sense when you can just give a civilian a polearm and tell him to fight. Not when you need an entire spaceship.