[Strategia_In_Ultima]

As I said, there's nothing to stop you from building Bombers filled to the brim with Interceptor weaponry. It's just that each type of fighter is larger than the previous one, and therefore can mount larger weapons. The Interceptors are small - tiny, even - fighters that cannot use many weapons, but are very cheap and can be produced and transported in droves, and can be used to overcome larger fighter's defenses to cover for the hard-hitting Bombers closing on the capital ships. SSFs can use larger, heavier, longer-ranged anti-fighter weapons, and are mainly useful (I think) for defending fleets against Bombers. Bombers are the only attack craft capable of using anti-ship weapons, and the Bomber anti-ship weapons are very powerful. A modest amount of Bombers can be more dangerous to a (2500kT!) Light Cruiser than a Dreadnought (somewhere between 15 and 20MT! There are currently three types of DNs). Bombers can be utterly devastating in the early game, if you research them you could gain a significant tactical advantage, however Interceptors and SSFs are far easier to research than Bombers and you could find yourself losing entire flights of expensive Bombers to swarms upon swamrs of dirt-cheap Interceptors.

Yes, attack craft (as I call fighters in Capship, since the Fighter denomination is mainly used to refer to SSFs) do have armor, and it can deflect most capital ship weapons.

Point Defense has practically been castrated, stock PD can only shoot seekers. You'll have to rely on other weapons (most notably Weapons Batteries) if you want to take on attack craft with a capital warship, but still the most effective way to counter Bombers - both economically and militarily - still remains Interceptors and SSFs.