Do you want to actually be in the park, or just to see the fireworks? Last year, we were able to get Narcoosee's reservations for 15 minutes before the fireworks were starting. I ended up cancelling because we decided to do the DVC party instead, but I had no interest in being in the park during the show. I loved the idea of watching the fireworks, but I didn't want to stand shoulder-to-shoulder with 80,000 of my closest friends. There are a few other decent non-park spots as well. I am sure California Grill is already filled, but you could always watch for cancellations if you want to try something like that. I actually booked the Narcoosee's dinner about 2 weeks before the 3rd, so it may still be possible to get something that works for you.
In terms of crowd levels, we found 4th of July last year to be fantastic. EP on the 2nd was pretty empty after a rain shower. We walked on almost everything. We did HS on the 3rd, followed by the dessert party. After the party at 10:00, it looked like the crowds were thinning at MK, so we wandered in. It was still pretty crowded when we got there, but it dissipated quickly. My older DD and I stayed until 3 for EMH, and by then it was empty. We rode BTMRR over and over at the end of the night, without even having to get off the last few times. On the 4th, we were back at EP, and I couldn't believe how uncrowded it was. We walked right up to Belle in France and had no wait at all to meet her. We were just in WDW for Jan 3-6, and it was much more crowded on those days than it was for Jul 2-4, 2016.