Probably anything; the density of the olive oil is greater than the density of water.
Yes salt sinks in oil and dissolves in water taking a portion of oil with the salt.
Another type of heavier oil.
Oil does not sink in water. Almost all oils and fats are less dense than water so they will float.
Oil is less dense than water so nothing can float in oil but sink in water. If it floats in oil it would have to be less dense than oil so therefore, it will float in water.