It's hard to give exact answers to your questions because so many variables can affect your visit, but here's my take for you.
Lines--Expect them to be long. July 4th weekend is very busy and some of tht will of course carry over into the next week. The park hours will be longer, but the crowds will be larger. Go with the expectation that the lines may be very long for some "big" attractions, and use Fastpass, Early Entry and (if they have them) Extra Magic hours in the evening. Check to see if there will be any e-ride nights during your visit. Don't let the crowds or lines ruin your trip. Just chill out, relax, and have a great time.
Movies--Is this your first stay in Disney? We have stayed at movies and had a great time. But we only use our room for sleeping, shower, and changing of clothes. When the parks are open, we are there all day, every day. The rooms are smaller than the moderate resort rooms, but the three in our family have had no problem. We always stay in an All-Star and will be back again in October at Sports. The Food Court offers the typical Disney food. Nothing special, but it serves the purpose. Might want to check out
www.wdwig.com for the section on Movies.
Weather--Hot, humid, and expect afternoon showers. Drink lots of water and have a poncho in your backpack.
Pack--Shorts, T-shirts, comfortable, broken-in shoes. You'll do a lots of walking. If you are going to one of the nicer restaurants, you might want to pack some dress clothes for that, but comfortable, cooler clothes for the rest of the time. And don't forget the bring SUNSCREEN. You can get a bad sunburn quickly and it can take away alot of your fun.
General--Read the boards, get some guide books for advance reading. Get the maps at each park for activities during the day at each park. Might want to make an plan for what park you want to visit each day, and check to see when Fantasmic, Magic, and the parades are held so you don't miss them. Have a great trip and send us a report!