Because of the rainy weather take your rain-coat, and an umbrella ...
Photo Equipment: Take all your photo equipment when possible. Digital could be satisfied, though telelenses will be better. Sensitive material is better because of the bad weather ...
Luggage and bags:
If possible I travel with hand carried luggage only, but my personal record with a claimed suitcase was to be at 7.30AM at the gate and be in my train at 7.50AM (with 10 seconds spare time!).
Checked-in luggage is the same as on any big airport. I had to wait on 2 occasions, but until now I still got my suitcase in the very end.
Clothing/Shoes/Weather Gear: Most of Schiphol is indoors and if you take the train or hire a car you won't need a coat at all.
Toiletries and Medical Supplies: Schiphol is well equipped. Bring your own tooth paste, shaving cream, dipers.
Soap and towels are everywhere and first aid is just around the corner.
Some of the lounges offer shower service.
Photo Equipment: The indoors lighting differs from hall to hall. Automatic compensation will not always do the trick. Make several pictures with different manual light compensation settings (indoors neon/bilb etc).
Camping/Beach/Outdoor Gear: Maybe a windjacket. It's a short haul to taxis shuttle- and busstops.
Miscellaneous: There are many shops around; with prices you can expect at Airports.