Can a furious weapon or bane weapon bypass aligned/adamantine or other DR if the increased bonus can reach a +5 (or greater) bonus?
Is there some reason to think they couldn't?
They lack the extra text that prevents other effects (Greater Magic Weapon/Fang) from bypassing DR normally, so there is no real reason to think that would apply in these cases.
The 'can I have a +6 enhancement bonus' is more questionable, but DR/Epic certainly implies its legal, thought you definately can't normally have a +6 (or better) weapon.