Tactics: It is Frogboy's opinion that a tactical layer is just a crutch for players so that players won't have to use their brains to do strategy. The reason for this is that players invariably find the exploits in the tactical layer, and then use them. For instance, in Acsendancy, you get Large hulls, and fill them up with the passive damage absorders, leaving just enough room for an engine, power plant, and a weapon. Then, you can fight all the tactical battles you want to, and never lose because your ships are never damaged. In MoO1, you get repulsors and a 2 tile reach weapon, and you'll win 99% of all your battles with zero damage, because your repulsors would push the AI ships out of 1 tile reach weapons, and the AI almost never made ships with 2 tile reach. 1 lone ship in MoO1 can hold off a mega armada (a fleet of 6 stacks of 999 ships) forever, and always win. In the first Total War, all you had to do was take 1 light cav unit, and run it from corner to corner, and you'd always win because the AI could never catch you. Any game with a tactical level of combat has numerous exploits. It's not a function of using tactics to beat the AI, its a function of maximizing the exploits to win.
Second, before the invention of the gatling gun, 99% of all casualties were inflicted when the opposing force tried to retreat. Alexander, Hannibal, Ceaser, Nepolean, none of them ever willingly retreated, because they knew that to retreat was to lose all their forces. There are a few occasions where a feinted retreat was called for, and that led into an ambush, but retreating from an on-going battle was not an actual tactic. They retreated before their opponents could engage them unitl they were willing, or forced, to fight.
Third, the "game setting" doesn't allow for opposing fleets to retreat. They don't just instantly warp away from one another (unlike in say, Star Trek or Star Wars). It's much more of an amphibious assault--- you know, a one way trip for the attacker. They either win (carve out a beachead), or they die trying. There is no retreat for this situation. However, once your fleet has attacked, if your fleet still has moves left, you can then withdrawl on the strategic map, rotate out the damaged units, rotate in new replacements, and then get ready to deploy back to the fight.