So I went through the tech document and I think I pulled out all the combat bonuses
To Boldly Go Combat Bonuses
So right now we benefit from improved shield regen, +3% combat in fleet battles, +5% combat when outnumbered, +1 L to all our ships if we start outnumbered by 2:1 or more, +1% to our combat vs Cardassians and Romulans, -1% to Cardassian and Romulan combat, 2% dodge vs Romulan and Cardassians.
A tech we may want to grab as soon as we can is 2320's Torpedo Tracking as that will reduce the evasion of opposing ships. Also the phaser burn through , getting all 4 would give us 11% burn through chance at which point our explorers could do enough damage to start dropping combat of the ship they hit. There is another 4% to combat from continuing the fleet comm techs.
Offensive doctrine is not included as we do not have the finalized versions up in the tech doc but there are likely several combat boosts in those trees.