After playing through a few sandbox modes, and the first couple campaign missions, here are some thoughts on combat.
1. So, there are the three offensive options (beam, missile, driver) and three defensive options (shield, point defense, armor). The exact details of defense are unclear. However, it's pretty clear that without any defense, 100% damage gets through (unless there's a miss). With defenses, it mitigates (but does not necessarily eliminate) the damage. Furthermore, it's not a 1:1 reduction in defenses. Generally speaking, it appears minimal defenses are useful, but overwhelming defenses are not.
2. In terms of combat type, beam appears to be superior and driver inferior. Notably, the beam defense (shield) is typically 1/2 of what the corresponding defenses are for missile and driver This means beams will deal with far less defense, on average. While missiles are useful for a first strike, pure missile boats can be overwhelmed by smaller craft due to the low fire rate. Drivers are simply too weak (1 damage for base level?) with accuracy penalties, short range, and armor being full strength.
3. However, the true winners (at least from the Terran campaign) in combat are Carriers. A typical "transport" Carrier (2 intercepter pods on a transport) will disgorge 6 Terran fighters...each with 15 beam. It's cheaper in cost than a normal capital ship, with a lower logistical cost, and if you lose a couple fighters, they regenerate next turn. Using this strategy, 3-4 transport carriers easily take on just about any other fleet.
4. Fleet mechanics basically seem to just have the two sides charge at one another. Classifying ships changes the original distance. That's the biggest bit.
5. What would be nice in terms of potential modifications (depending on AI adaption).
a. Ramp up driver damage or fire rate.
b. Potentially differentiate how defenses react to damage type.
c. Potentially make ships with sufficient defenses immune to damage from "too weak" attacks.
d. Make thrusters worth SOMETHNG.
e. Introduce fleet tactics. For example "Stand off". "Drive to Starbase" "Standard Engagement" "Defend capital ship" "Destroy support ships"