Yes, you can walk from SSR to DTD. It's about a 10minute walk from the Congress Park Bus Stop and we found the walk to be quite enjoyable! It wasn't as well lit as we would have liked, but we feel safe and secure, even when walking by the main road. SSR also has a bus and boat to DTD which would help out if your planning on heading to PI.
OKW has 5 bus stops within the resort; you can find a resort map here showing where the bus stops are in relation to the buildings and main building: http://www.wdwinfo.com/maps/OKWMap.pdf
The bus at OKW stops as follows: Peninsular, South Point, Old Turtle Pond, Millers Rd, & Hospitality House. There is also an internal bus to take you from one part of the resort to another.
The wal to DTD is what has hooked us on SSR. After a day at the parks with my son, he will fall asleep on the bus back to the resort and then we stick him in the stroller and we get a late night snack and "Drink." All the while he is resting up for the next day