Yes, YC and BWI are next door to Swan/Dolphin - you can walk or use an ECV to get to either resort. You can also take a Friendship boat to either resort from the Swan/Dolphin boat dock.
Just be aware the buses from the Swan/Dolphin are no longer WDW Transportation buses. At one time they were coach style buses, but that may have changed. The drop-off/pick-up at MK will be at the TTC with other offsite resort transportation rather at the WDW resort bus stops.