In WCP, to survive in a bomber, USE YOUR ESCORT! There's a reason that you are assigned a fighter escort, after all. I find that the hardest bomber to survive in is the WC3 Longbow. Its Neutron guns don't have enough range to kill an enemy fighter before it gets close, and it turns too slowly to chase a Darket when it gets close to you. Instead, you need to use your missiles, and also order your wingman to "help you out here" whenever an enemy gets on your tail.
Personally, however, I avoid using the Longbow and just take the Thunderbolt instead. Since capships have a blind spot over their engines, the easy way to kill them is to afterburn in from behind and match speed, sitting right behind their engines and pounding away with full guns. This works with everything except the Corvette.