It is water-resistant. This means that it will be fine during rain, but you cannot submerge it.
Absolutely. Just release the Fidlock snaps and you'll have all the space you need.
The Edge45 Duffel is the same capacity as the Original King Kong Duffel but has many differences. This bag is fully lined with more internal compartments in the main area, as well as cleaner lines. It is slightly more water-resistant, and the shoe pockets are on either end and can be external to stop the shoes from taking up internal space. It also has capacity for a 15in laptop in a padded sleeve at the back.
The Original King Kong Duffel is more of a 'pure gym bag' whereas the Edge45 is closer to the middle on the gym-lifestyle-work spectrum of bags.