As for tips... One word for ya....FASTPASS! When I was at DL for Christmas, we noticed that there were always FastPasses left late in the day. Not at WDW in the summertime. We run out quite early on busy days. Fastpass is the way to go. Especially since it will be very hot here then.
EPCOT, Animal Kingdom and the Studios will take about a day each. Magic Kingdom you'll want to spend around 2 days. After that you could go to Universal and Islands of Adventure. Or try a water park. Blizzard Beach is cool, but not a lot of shade for those really hot days. Typhoon Lagoon is much more shaded.
At night you could go to Pleasure Island. On certain nights, cast members get in for free. And at House of Blues, service industry employees get in for free on Sundays with great drink specials.