You can only get 1 piece of the lumberjack outfit per event. If you do not receive a piece during the first wave, wait and keep trying. Wearing the full set gives 2.5% bonus experience to woodcutting. Additionally, using an infernal axe will also grant bonus experience to firemaking. The Lumberjack outfit's bonus does stack with the bonus 10% experience when cutting maples from the Kandarin Diary medium reward.