Not having stayed anywhere except OKW, I do';t know the "name" of the store at your resort (sorry), but yes, everything on the fax list should be carried in the store on a regular basis. The may be temporarily out of stock on an item, like if EVERYONE was suddenly in the mood for a box of frozen waffles

, but generally everything should be available.
One nice thing about calling prior, they may be able to tell you if any particular item IS out of stock, and when delivery is expected. Since there is a delivery service charge added to the order, I would not think a tip is necessary, but I'd probably offer a small one anyway.
Also, when you call to confirm your order, you could ask for the procedure as to whether you should call from your room or if it will be "automatic". My guess, though, would be that you'd need to call, since room assignments
can change and housekeeping will have rooms ready at different times throughout the day.