While I have been there and experienced it, these planning sites say it best and give a good discussion of what you will face and have to plan for:
http://www.easywdw.com/calendar/july-2014-walt-disney-world-crowd-calendar/
"The Magic Kingdoms Celebrate America Firework show is one of the best of the year, featuring panoramic fireworks shot from all around the Park. Its a much more exciting, much more expensive, much more substantial show than you would see on any other night, other than perhaps New Years Eve. To guarantee admittance, youll want to arrive by 10am and stay in the Park for the entire day. Because its so crowded, it will be difficult to get on any attractions without waiting at least 30 minutes and all of the major FASTPASS attractions will likely have waits that exceed 100 minutes in the afternoon. The only time youll find reasonably short lines is during the first two hours of operation and potentially after 10pm."
This one is great too:
http://**************.net/2013/12/18/july-2014-at-walt-disney-world/
"July crowds begin high, with trips that include the 4th of July weekend (the 4th is a Friday in 2014, so it affects both its own week and the week after) facing the worst crowds.
Crowds are a little better after the weekend of the 4th, but still high.
On a crowd scale of 1-11, the week beginning 6/28 has a crowd rating of 10/higher, the week beginning 7/5 11/highest (especially over the weekend), and the rest of the weeks of the month 9/high."
Hope the info helps!