I honestly believe that's the biggest helpful hint is having other players know what to do. If you watch my video, all the battleships leave the harbor structures to me, the Farragut, and the other cruiser to destroy. The battleships immediately turned around to deal with the enemy reinforcements as we swept the base clean.
As for the enemy ships, the destroyer to the south that I encountered LOVES to fill that opening with torpedoes so watch him when you go in, and if you have Hydroacoustic Search, use it when you spot him. Radar would help if he smokes up. The cruisers will do nothing but harass you, whittling your heath down so that when you have to destroy the battleships, they can pick you apart a salvo at a time. The buildings in the harbor are fairly weak, so I like to fire a salvo from the front two turrets of Dallas at one structure, then use the two rear turrets of Dallas to hit another structure. Of course Dallas doesn't have torpedoes, but mine has IFHE and Demolition Expert for her 152mm HE shells.
Killer Whale is probably my favorite Operation, and the only one I got 5 Stars on.