The bus is a good idea - IMHO, better than going through the TTC. It will avoid waiting for more than one form of transportation and will probably be a lot less crowded than leaving for the TTC.
If the bus service is combined for the BWI, BWV, YC, BC, Swan & Dolphin Hotels, get off at the Swan (first stop) and walk to the IG entrance of EPCOT. The IG entrance is between the France and British pavillions. As noted, you won't have to walk through Future World to get to the WS - you'll already be there after you enter EPCOT!
At closing, the MK bus service for the Swan & Dolphin is usually separate from the other hotels. If so, jump on whatever bus comes first and get off at the first stop. That will be the YC if you get on the BWV, BWI, BC & YC bus. You can then walk to the IG entrance from there.
Good luck!