scoring in attack mode gives you fighter perks.
ack-ack
Not necessarily. It depends on the plan's primary role, not on the scoring choice made by the player.
Fighter/attack planes always gain fighter perks
Bomber/attack planes always gain bomber perks.
The selection by the player in hangar is just for scoring
Note that the Il-2 only seems to be the only pure "attack" plane, but it's a fighter/attack in wich the fighter
scoring option has just been hidden. With this trick (changing from bomber/attack to fighter/attack) HTC did remove the F3 capability, which is currently tied to the plane category and not individual planes.
Just adding the "attack" category to the B-26 won't mean you will gain fighter persk in it - it would still be bomber perks.