[douglas]

The combat simulator uses the racial combat modifiers of the first ship added to a particular side for all the ships on that side. Once you know any ship design at all of an enemy, you can determine that enemy's exact racial combat modifiers by putting that ship in the enemy force first, followed by one of your own warship designs, and observing the to-hit chances in tactical simulation. You can even remove the enemy-designed ship from the force, and as long as you don't exit the simulator completely, it will still use the enemy's racial combat modifiers for that side.

I believe the simulator uses the actual strategies that the designs are set to, and may actually use the enemy's customizations of strategies when you set an enemy fleet's strategy in the simulator. In simultaneous movement games, the strategies you see in the simulator will lag one turn behind any changes your opponents make, but it can still be pretty useful sometimes.