If you're there for Hoop Dee Doo anyway, I can't see any reason not to go ahead and give the campfire program a try. If you don't like it you can always leave, but I think you'll probably like it. For watching the movie, it's true that there are metal bleachers (with no back rests), but in front of those there are also log benches that do have backs - try for one of those if you get there early enough. They're not super comfortable either, but they're better than the bleachers. The most comfortable of all is to take your own camp chairs, but that probably won't be practical in your situation.
It is possible to walk there from Pioneer Hall, but it's a bit of a hike, and a little confusing in the dark, so since it's your first time, I'd take one of the internal buses instead. Just tell the driver you want to go to the Campfire program, and he (or she) will let you know what stop to get off at.