One way I've managed to prevent a few (2) casualties is to tell my wingmen to form on my wing and stay there during the first strike ("Torpedo Delivery" against the escorts). That usually means I come home with at least my wing of 3 Sabres intact, although that also usually means I don't meet with complete success. I'm guessing that if my wingmen aren't in there joining the torpedo strikes, there are more defending fighters and flak that the remaining Sabres have to deal with and that means they usually get knocked down before they can take out enough capships.
I don't know, it might help. If you fly a Sabre for the Hakaga strike, the Firekka doesn't seem to launch any Crossbows. That means that if you lost a lot of Sabres last time, you might be in trouble later in Ep. 4 (win), because if you need to fly Sabres in any later Ep.4 (win)missions, it looks like you need at least 3 Sabres on the carrier to go on.
Forgive me if my memory fails me - but I think the Firekka starts with 12 Sabres at the beginning of Ep. 4 and launches 6 Sabres in the initial strike against the escorts. Suppose you lose 5 of them, and come home yourself (in your own Sabre). That leaves Firekka with 7. If you fly Sabres out against the Hakaga, I think Firekka launches 6 again. If you lose all the Sabres but your own and return home, that leaves just 2 Sabres on the Firekka, which is probably not enough for the rest of the episode since there are other missions where you launch as the lead in a wing of 3 Sabres. Afaik, Firekka doesn't receive any replacement Sabres or Crossbows for the rest of Ep. 4 (win).
The Hakaga strike is the only time in the Ep. 4 winpath that I've seen the Firekka deploy Crossbows, so if you find yourself running short on Sabres after mission 1, try to beat the Hakaga strike with a Crossbow. It may bore you to death, but you should be able to continue.
I think they've hinted that your fighter count coming out of Ep. 4 may affect what you start with in Ep.5. If so, I've got a problem - on my watch, only 2 of the Crossbows came back from the Hakaga strike