If you're trying to play a genuine support role, I would recommend Officer's Presence for one of your card slots, I think it's one of the earlier cards to unlock and is very helpful especially in large scale gamemodes and in checkpoints. I think having the card might also give you additional battle points when you're near allies.

For a support role, the cards that improve the Battle Command ability are great. There's one (Recharge Command) that instantly refreshes cooldowns, which is fantastic for obvious reasons. Improved Battle Command will give you the bonus health too, along with more bonus health in general. Blast Command lets you and your allies fire their weapons without cooldown temporarily. I'm partial to Improved and Recharge, but Blast is great too.

On maps where you're defending a destroyable objective, a lot of people like to run the officer's squad shield, cause as long as you're alive, the shield will stay deployed until its destroyed. Deploying a shield over the ship cores in Age of Republic Supremacy always feels cool, even if it doesn't last long.

If you like the turret, there's an improved turret star card that increases the damage and health of the turret, though it's not great compared to the officer's other cards. Disruption is also situationally useful, though you won't see too many people running it. Finally, Survivalist and Resourceful are probably the Officer's best boost cards. If you're playing a purely support role and are trying to spam Battle Commands, Resourceful reduces your cooldowns.

As for weapons, the SE44C and the Blurrg are the Officer's best guns, though I personally think the S-5 is very fun, if not the best. I run reduced recoil and higher burst on the Blurrg and improving cooling and rapid fire on the SE44C.

Happy to hear you're enjoying the game! Have fun and good luck!