If you look closely to the Dracon beams the Controllers are holding, its actually just flashlights, modified to look alienic.
By the books, Visser Three is only the rank of the Yeerk. His name is Esplin9466. The Andalite-Controller's name is Alloran Semitur Koras.
According to the first book, the monster that Visser 3 changed into is an Atrianian swamp monster that he found on a dying planet.