Boats from WL go to MK, or the Contemporary and Fort Wilderness. The one to MK will also stop at FW, that schedule depends on time of day, season as far as order of stops. The resort boat could get you to the Contemporary for 2 monorail access to Epcot, but that would be a long trip!
Yes, bus is best. You will have to stop at one other resort on your way to EP (can't remember which one, Poly maybe?). Boats only go to FW, MK, and CR. Taking the boat to the CR you could then take the monorail to the TTC then switch monorails to the EP monorail, but that would take a long time.
The bus doesn't stop at the monorail resorts, which are already connected to Epcot through the TTC. The Wilderness Lodge bus shares Epcot transportation with Ft Wilderness.