I will say that the boat is very close to the time for walking. I left BW, just by the boat area, walking to Epcot, last Dec. As I started walking, the boat pulled out and headed directly to Epcot. I walked at my normal pace (may be a bit faster than normal) and I got to the unloading area for the boats by the International Gateway, just as the guests were getting ready to get off. But, if you're at a different resort, it's going to take longer for the boat to get you to Epcot...BW is the last stop before going to Epcot.
As for walking to DHS, it's a very pleasant walk, along the canal. I've walked it after dark and felt quite safe. It is very well lit and open. It can be brutal though, in the middle of the summer. The heat/humidity during the daytime can be unbearable if you make that walk. So, take that into consideration as well.