It depends on the MK firework schedule - check the app to be sure. Keep in mind, while you can definitely see the fireworks, it's a high view over the trees. This isn't like sitting on the beach at the Poly or a theme park view room at the Contemporary. Still, it is a lovely way to end the night. We stay at Wilderness Lodge a lot as our DVC home resort is Copper Creek and we adore eating and hanging out at GP. We love the views - it's like not even being at a theme park - so peaceful. And if you go for lunch, it's rarely crowded (hint: it's just a short, lovely boat ride from MK if you need a break mid-day).
As for the burger debate, I think both of them are good, with maybe giving the nod to Three Bridges by a tiny bit. The food options in general are definitely better at TB over GP as well. But what GP does have, is usually really good. One thing that I really liked about TB over GP was the drinks. GP's cocktails are basically your typical fruity, sweet pool bar drinks. A lot of people love that, but they aren't our thing and the wine and beer selection is limited. TB has some really interesting wines, fun cocktails and some really good sangria.