House Ordos is not featured in any of the official Dune novels. They only appear in a list of Great Houses in 'The Dune Encyclopedia', a non-canon work that describes many details of the Dune universe.
The game was not supposed to be a sequel to Dune (1992). What happened was that Virgin Games USA had obtained the adaptation rights to the Dune novel and the David Lynch film, and tasked a French development team (the later Cryo Entertainment) with adapting it into a game. However, the Americans were not impressed with the initial designs, so they backed out and ordered Westwood Studios to start with a new version from scratch. Since so much work had already been done, the European office of Virgin kept secretly financing the French version, even though they no longer had the adaptation rights. This game was finally released by Cryo as Dune (1992) with the approval of Virgin USA. The Westwood version, which appeared later that year, was therefore re-titled as Dune II, even though both games have very little in common except for the source material.
Emperor Frederick IV appears only in Westwood games; he is not mentioned in context to the other canonical Emperors. His role in the games is similar to Shaddam IV of the original Dune novel.
A largely unknown but very curious feature in Dune II is that a small amount of credits is frequently subtracted from the player's budget, the amount directly proportional to the current power consumption in the player's base. In other words, the players pay for the power they use.
You can make a mentat blink or move its mouth by clicking on his eyes or lips, respectively. The same is true with the girl telling you about the houses at the beginning of the game.