Depending on the time of year you go you would def not want to walk that in the heat. I would personally probably not walk that as it is a bit far in the Florida heat. It would be much easier to drive there.
You could take a taxi, its really not far, but its a very big intersection that you would have to cross, and if your going to shop or buy groceries, it would be no fun lugging them back.
The Hotel Plaza Boulevard buses are just for those hotels' guests. They used to give you an ID card to show as proof you were entitled to ride the bus.
DH and I have walked to Goodings several times. It's not really that far and mostly shaded. There is a crosswalk at the intersection. The first time we carried the plastic groceries bags back and it got a little heavy and uncomfortable on the hands. The next time we took a backpack and it was better. Our last trip (May 2007) we had a rolling soft cooler that we had bought for the DCL last year. This was the trick! The heavy drinks went in the cooler and the lighter snack items could be rolled on top. DH carried the cooler and I carried the bags on the bus from DTD to BWV.