I'm having a hard time understanding how fleets and combats work in this game, and the AI is kicking my ass as a result.

I'm playing what passes for the tutorial (default settings, small 2-player map, mirror match with the United Empire). Our point of contact is the system containing Auriga, which is a nice touch. Since it's Barren I'm guessing ES is chronologically much later than EL?

Anyway, I sent a 10-ship (max cap for my current tech) destroyer fleet to try to push the AI fleet off. We have a 10 vs. 10 fight, equal tech (as far as I can tell), each losing four destroyers, with the AI fleet more damaged than mine since most of their remaining hulls were scout-type. So far so good. The problem is that the instant the fight ended, the enemy fleet consisted of 12 ships (apparently they've researched one more military tech than I have), not 6. OK, I can reinforce too, I sent four ships from my nearby planet, to arrive the next turn. End turn. The combat interface pops up, I have my reinforcement fleet execute its movement, so I have ten ships in system. Unfortunately the game won't let me merge them, so it's a 12 vs. 6 fight, I kill four destroyers while losing all of mine. But wait, it gets worse! Instead of my reinforcements facing a 4 vs. 8 fight, they're at 4 vs. 12, with a fresh cruiser and two new destroyers joining the enemy. :(

Why does the AI get to reinforce and merge its fleets between combats, but I don't? The only thing I can think of is that their connection to the system is a wormhole, so is there some weird rule that ships arriving via wormhole can merge into existing fleets, but ships arriving via strings can't?

My second issue with combat in this game is the perception that the options are autocombat or autocombat with cinematics. Does "manual" combat actually let the player do anything to affect the outcome? I haven't been able to find a way to pause, or get any tooltips to identify the ships on screen. The only way I can tell which fleet is which is by seeing which side along the bottom of the screen gets an X through a ship icon when a ship blows up. It looks like the only thing the player can do to affect combat is picking the three phase cards at the very beginning.

Is there any way to see for certain what tech the AI is using? I'm guessing from the even results that they don't have the t2 kinetics tech either, but it would be nice to know for sure.