If you're coming for ski jumping, make sure to have warm jacket and trousers (ski trousers would be best), also good shoes/boots to keep your feet warm as you'll be standing for 2-3 hrs on cold ground. Warm refreshments were available at the stadium at very affordable prices.
Photo Equipment: Make sure you've got enough film with you as you can get very close to your favorite jumpers and take numerous pictures. Also a pen and paper for autographs if you're after that.
Luggage and bags:
Anything you like. When moving around a lot, a backpack might be more handy then a suitcase.
Clothing/Shoes/Weather Gear: In summer it's very warmn here, but keep in mind that rain can always fall here. In the mountains clouds can come up very quickly so bring a long that umbrella, those boots and that raincoat!
Toiletries and Medical Supplies: Mmm maybe some suncream when you go in the mountains.
Photo Equipment: Enough film is sold here to let your camera click all day :)
Camping/Beach/Outdoor Gear: Campings are to be found here a lot, so yes you can bring your own tent and sleeping bags if you like camping.