The Tar-Siti Empire (my current game)

[Iron Giant]

Well, I've been around this game for a while, but am by no means an expert. I'll comment anyway, since your looking for it

No, you cannot upgrade units (fighters, weapon platforms, mines, satellites).

Also, on a Destroyer class ship, I prefer to skip shields, set the ship tactics to "maximum weapons range" and put on all the missles I can. IMHO, mixing weapon types (direct fire and missles) is a bad idea. Too few missles and they can be shot down with point defense. Too few direct fire and a miss is a real let down. Early on a small fleet of destroyers packed with missles is a real threat.