Dwarf refers to a person with one of several varieties of a specific genetic condition called dwarfism. A dwarf has disproportion of body parts. This is generally caused by a genetic or nutritional disability. Any adult human below the height of 4'10 (147 cm) is considered a dwarf.
One Piece has a great story and does not have a lot of filler episodes.
Fillers are what killed Bleach. There are 205 canon episodes and 161 completely anime-only episodes, so with a series where nearly half the episodes are anime only , you are going to have many problems. Other than the obvious fan displeasure, filler arcs are much more of a financial risk.