Yeah I always go to mark 3 econ stations relatively early. And I also notice that I'm always upgrading metal harvesters to Mk 2 or even 3 pretty early game as well. Although I don't know how effective that is, to be honest. It seems like the increases for them are more balanced around late game, with a lot of planets. When you're only sitting on 4 or 5 worlds, getting an extra 8 metal per harvester doesn't really add up to a whole lot.
And yes, I do tend to put my fighter/bomber/frigate builds all on loop, along with whatever starting ship I get. Turret wise, I am sort of haphazard. For general wormhole defense I will probably go with a couple grav turrets, 3 or 4 mines, and then maybe 5 standard turrets and 5 lasers. Then I might just randomly pick some of the other turret types for the heck of it. I'm not overly strategic with my turrets, to be honest. It's probably something I should look into, if I ever get better about recognizing what turret counter is best for what ship type. I tend to be sparing on sniper turrets and I usually don't get spider turrets unless I find the AI favoring raider-style ships.
And yeah, my current game isn't using fallen spire, but I do recall how much crystal those ships eat up. It's crazy.