There aren't cheats, per se. I think you can turn on invulnerability and unlimited ammo (Maybe?) in the game menu.
Red Manta Bombers use torpedos, you can't target them in flight, you have to manually eyeball them and shoot them down. Barracudas also use torpedos.
Skates use energy (plasma) weapons. They need to be in clusters - groups of three merged together to use this weapon, so blowing up a group and then targeting just one of the skates to kill means they won't be able to goup up anymore. However, if there are more then three skates left, they can. The Skates (IMO) are more dangerous then the others, as their plasma weapon can rip through capships quite quickly.
Lastly, make sure you are using (L) to lock targets. I've found that when you blow up a target the game randomly assigns you another one as long as it is locked - however, often times you can see when an enemy ship is about to explode, if you change targets before it does, it will often (but not always) skip assigning you a new target if you already have one.
I find the best thing to do when targeting bombers is to find a sequence of them (where you can see two or three in a row via the T and Shift-T keys) and start at the top. That way to reach the next one all I have to do is press T.
Additionally, it helps if you check (repeatedly) the distances of the enemy fighters.A Manta roughly 5000 m out is probably more of a threat then one 50,000 m out. Last point of references: Ships about to launch a torpedo fly in a straight line and don't shoot and sometimes don't dodge shots that are incoming (or striking them). This is also a quick visual way to identify bomber targets.