A balloon filled with hydrogen or helium will rise into the air simply because the density of filled balloon is less than the air. The density of styrofoam is greater than air so it will not rise into the air, however the density of styrofoam is less than water so it will rise through water. It has nothing in the slightest to do with 'anti-gravity' or entropy.
Not sure what you are talking about, but if you are referring to the attraction between a balloon and aluminum this is the reason. The balloon is an insulator and when is rubbed there will be a build up of electrons on the outside of the rubber. If a piece of aluminum foil, which is a conductor, is placed near the balloon there will be a migration of positive charge to the side of the aluminum foil that is nearest the balloon (due to the negative charge on the balloon attracting the mobile charges in the conductive aluminum). If the charge on the balloon is high enough the electrostatic force will be greater than the force of gravity and the foil will move to the balloon.
Again there is no magic, no anti-gravity or entropy involved.