Well since Conan is essentially an ancient Celt, raiding is a very Celtic past time. If I had to give Conan an alignment, I'd call him neutral - able to go in any direction, based on how the wind is blowing or where the threats and opportunities lie.
While Celtic raiding was mostly stealing cattle (so stealing is obviously OK with Conan), slaying clan enemies, taking slaves, burning buildings/villages are part and parcel to raiding activity.
I don't think I remember any Conan activity involving rape directly. Forceful sexual advances might fall under rape in this day in age, but not so in Conan's days. Conan had plenty of voluptuous encounters (I think voluptuous was Howard's favorite word - it was used a lot in Conan books) that didn't involve rape.
Raiding is seldom the total destruction and death of a village's inhabitants. Raiding is mostly taking stuff. Its never complete genocide.