It's very easy to walk to World Showcase from BWV. By the time you walk to the Boardwalk boat dock, you're only 5 minutes from Epcot on foot.
The entrance to WS, whether arriving by boat or on foot, puts you in the park on a little pathway located between England and France, as the previous poster mentioned. The friendship boats that go to the resorts and the Studios end their trip in a dock here, on the resort side of the bridge and outside of Epcot's turnstiles. They never go under the bridge into the WS lagoon.
The boat stops you see near Morocco and Germany are different boats ... they just go back and forth across the lagoon from the Port of Entry area (where you cross from Future World into WS) to the other side of the WS promenade. They never leave Epcot, and you have to be in the park to use them. To get on those boats, you'd have to get off the resort boat at the WS entrance, go through the turnstiles, and then walk around the promenade to the queue. It is often faster to walk to Epcot from the resort than to take the boat. In much the same way, it's faster to walk around the WS promenade than to take the internal boatride across the lagoon.
