I neck size only in new brass, in all other brass I full length size. To each their own though.
The reason I only neck size in new brass is too just straighten out the necks since they get bent in shipping. New brass should be within specs already.
That's just me though. Each person does it differently.
On OAL, I generally set .03-.02 from the lands. I know some that set .002 from the lands. I haven't quite gotten that brave yet though. I get within .500"-.600" spread with .02-.03 from the lands though in my rifle.