Dont get your carb serviced or tuned. Its on factory settings and believe me, this way the fuel economy is really good. The moment you service the carb or get it tuned by any ustaad the fuel economy will reduce significantly. Its better you change the oil. The first oil change should be dont at 200km-300km, reason being the metal shavings mixed with it as the engine is breaking in. Dont wait for the color of viscosity to change.
Use iridium tipped spark plugs if the FF is not performing up to the mark. What problem are you facing that prompted you to think of changing the spark plug.