No, it is not. The current smaller version is made of water resistant nylon, but still gets pretty sweaty. The larger version was created with waterproof lining on the inside of the zipper pocket, and encased in the back flap section. It still is not waterproof if you are running long distances in the heat. Sweat can tend to seep through the zipper. In these instances we recommend that you place your electronics in a Ziploc baggie. For most of your normal runs it keeps the moisture out.
The RooSport is designed to be worn on the inside of your waistband. However it can be worn on the outside it you are not carrying anything heavy enough to bounce. Wearing it next to your body on the inside, coupled with the strength of the magnets makes the RooSport very secure and it is very comfortable.
Yes, in most cases your hotel room key will be wiped out with this magnet. The hotel keys use very inexpensive magnetic strips. Your cell phones and other credit cards can also wipe out your hotel key. I still carry my hotel key in the RooSport; I just alert the front desk when I return that my card has been near a magnet and they fix it before I go to by room.