As far as the grease goes the reason why you put grease on anything your torqueing is so you get more accurate torqueing not sure why you should put any on the splines unless it makes it easier to remove down the road this way. and as long as you hear that torque wrench click then it doesent matter if it's up on jack stands or not. I dont see how that dang nut is comming loose. Try some lock tight red.