Lens tilt offset and View Camera bellows

Does anybody know what the lens tilt offset is for a 150mm lens that is on a view camera focused at infinity and sits 5.5 ft off of the ground? (I'm referring to the offset in the image circle) This is for landscape and the lens is downtilted. Also will the focus shift on distant objects when the lens tilt is varied even though the lens is focused at infinity? What are the advantages and disadvantages of having a leather bellows instead of a synthetic one? Which is better?