1- I believe that hayride will take you to a special spot along the beach to view the fireworks.
2- The fastest way to get from WL to the campfire would be to take a bus from WL to the settlement and then on the appropriate interior bus. The orange one I believe.
3- The petting farm is no longer there. When we were there last April there were a few goats, a pony and maybe a sheep. I'm pretty sure someone reported recently that everything except the pony was gone now.
I'm sure others that have been there more recently will chime in
Shannone is right, there are horses and that's it. You will need an interior bus for the campfire (or you could walk) but you won't for the Hayride. You check in near the Settlement across from the Hoop-Dee-Doo-Review.
It's been a few years since I've taken the wagon ride but my memory tells me (take that for whatever it's worth) that we did see some fireworks but never stopped or tried to find a special viewing location, you can't hear the music anyway and I don't remember it being even a small part of the wagon ride fun we had.