3 - bombers are FAR to strong. They're very difficult to destroy without flak bursts (inta kill)
You can build Flak Frigates right off the bat with no research. Just assign them to a different group than your fleet (so they don't get your focus attack orders) and set them to follow/protect one of your main cap ships. They eradicate fighters and bombers alike very quickly.
If you mean your bombers are too strong, once the AI is smart enough to use Flak Frigates well, you might not think so, they are very fragile.
I think the bombers are just right atm, your supposed to be afraid of bombers because they hurt like crazy, thats why you build to defend agaist them and why they are pretty easily defended against. If your enemy doesn't, well, thats a game win for you.