SO YOUR ROSHI! haha! Ok so I definitely lost ships but I think it was due to bugs because I would take 3 planets and not lose anything and then suddenly lose a battlecruiser on the next planet.

The way combat works is that the attacker fires first unless the defender's mining colony has ships in orbit(not sure about orbitals) and he has the attacker set to war instead of peace in diplomacy. In that case the attacker would lose ships, maybe he would lose enough to lose the battle in the second or third round of combat but that is based on how many ships he entered with.

Are you using stealth orbitals? Because if you are they don't seem to be having any effect on my dreadnaught fleets. Also I think you just lost your entire fleet at my mining colony