You can cut over from Tomorrowland to avoid the hub at the Castle, you end up by the Plaza restaurant, but you still have to go down Main street to exit the park.
I'm not sure what you mean by the DVC....do you mean the TTC? When you exit the MK go to the left to where the buses are and you can get the bus to the BC and the Boardwalk Inn.
To get to Epcot from the MK by monorail, you can do one of two things, take express monorail to the TTC and then the Epcot monorail from there, or you can take the resort monorail to the TTC and then the Epcot monorail. (Generally, the resort monorail has shorter lines)
You then have to walk through Future World and Worldshow case to the International walk way to get to the BC or BWI.
Personally I think it would be faster to just take the bus from the MK to the Bc or BWI.