Most of the knockoffs were actually made by a limited number of major companies - Stanley, Millers-Falls, Sargent, for instance - often whoever was the lowest bidder during a contract period. Often, the only reliable marking on such a knockoff is on the plane iron. So, absent other information, you can assume you've got a Fulton. No big thing if the quality's there.
As to sharpening the molding plane iron: there are slipstones available, shaped to fit the iron; for a simple pattern like that one, though, you can probably get the job done with wet-or-dry sandpaper wrapped around a suitable dowel, lubed with mineral spirits, kerosene, or the like. Just pay close attention to the shape of the iron and don't inadvertently change it.