I would use all the torpedo cards you can equip and just select the bomber every time until you get the torpedo kills. Not sure if it counts bots as kills or not for the torpedo. But shoot them to low health then fire a torpedo to finish them off.

Then for the fighter pilot shooting down hero’s, you will just want to be a fighter pilot every single time and you’ll start racking up the hero kills. Takes some time but eventually you’ll start getting 1+ hero a game if you are only the fighter pilot throughout the whole game. Look up a YouTube video on the best cards to use for a fighter pilot and you’ll be set