The AS Cadet would probably work OK as long as it wasn't defective. Pros like Terry and Redwood report many factory defects. The Niagara is really bad news, so it's good you stayed away from that one. Two of the four bolts on the old one go into the floor. The other two into the flange. You are spending a bit more for the Drake II, but you are getting a better toilet. I'm not sure what to use, but I do not you want to stay away from abrasives that will damage the Sanagloss, and are totally unnecessary on the exterior anyway. Your dealer should be able to recommend a good product and may even sell something. Hang around the forum, there will likely be some good suggestions.