I sort of agree with you on the whole Roleplay elements, but I'm pretty sure it will not be a skill that can be leveled up, unless its added into the Alchemy skill, in the way that preparing food with different ingrediants will level this skill slightly more than just eating ingredients, but less than making potions.
Having said that I think that it should be instant with no waiting around, like the potion making.
But this should be all part of Realism Mode, similar to FO.NV hardcoe mode, so that players can choose to use this or not.