As to whether to use 2 or three bladed props, not a really important decision. Both will work equally well although at the small size our model props are (relative to the size of the molecules of the air) the three bladed props will be slightly less efficient. However, if you properly size them either type will fly your model quite well. In general, the three bladed prop gives you more ground clearance as the blades must be shorter to keep the same load on the engine that an equivalent performing two blade prop would require. As long as the one you have on the plane does not over tax the engine, use it and have fun.