When staying at BWI (the Inn side) and walking to MGM, cut through the main pool area, it's a short cut to the walkway. We really enjoyed the walk to MGM. Very quiet and peaceful. I think we only took the boat once and that was coming back in the rain.
Walk or boat to EPCOT.
Bus transportation to all other areas. Bus is shared with Swan and Dolphin - 2 separate stops and sometimes Beach and Yacht Clubs.
There is an alternate way to MK, but it is longer and involves more walking. If you are not in a hurry you can try this. But if you have meal ressies, don't try it.
You can walk or boat over to Epcot. You enter in the World Showcase. You can walk to the Main Entrance, on the other side of Space Ship Earth. Leave the park and take the Monorail to MK. When you arrive you have to either switch to another monorail or take the Ferry. But this is the long way.