EPCOT newbie

Epcot is a great park, but it's pretty different from a normal amusement park. There are relatively few rides, but the rides tend to be larger in scope than what you'll find elsewhere. There are also a lot of films, exhibits, and smaller offerings to fill your day out with; you could easily spend all day there without going on a single "ride"

For FPs, the biggest draws are Frozen Ever After, Test Track, and Soarin', though with the tiered system you'll only be able to pick one of those. Test Track has a single ride line which can help (though often has an equally long wait as standby), and Soarin' recently added an additional theater to boost capacity. Frozen is fairly low capacity and very popular, so the lines will be long and FPs are probably already gone for your dates. Most of the lower tier attractions are very high capacity and rarely have waits more than 10-15 minutes (aside from Spaceship Earth early in the morning, since it's right at the park entrance), so those FPs are all varying degrees of worthless

It's best to book your FPs as soon as possible. Obviously the downside to this is that you have to purchase tickets in advance, but the closer to your date you get, the fewer options there will be. Especially since it's the busy summer season, I'd err on the side of doing it early

Because the park originally focused on high-capacity attractions and shows, many worthwhile attractions don't offer FP. One of my favorites is the American Adventure in World Showcase. It's an animatronic/multimedia show of US history, and is still a technological marvel 35 years after opening, while also managing to be relatively entertaining. Plan to get there before the show to hear the Voices of Liberty (check the times guide) perform a capella folk songs in the lobby; they're great!

The Universe of Energy is set to close in a few months (rumored to be replaced by a Guardians of the Galaxy rollercoaster), so if you have time, it will probably be your last chance to do it. It's long (about 45 minutes including the preshow), but it will show you just how bold and different the park was when it opened (even though it was dramatically changed in 1996, and maintenance has been poor in recent years)

One of my personal favorite out-of-the-way things is Impressions de France, the movie in the France pavilion. It's pretty much a standard travelogue with very few 'gimmicks' to make it stand out (other than the wide screen), but it's just very nicely done and really enjoyable. Plus it's a great way to get out of the heat for 20 minutes

Especially in World Showcase, it pays to get off the main walkway and do some exploring. There are lots of hidden corners and small exhibits that are fun to explore. The pavilions are all staffed by natives of their respective countries, so there are great conversations to be had. The food and drinks can be a lot of fun too

As for clothes, as long as you aren't wearing something offensive or overly-exposed, wear whatever is comfortable for you. It's a theme park, not a fashion show; people won't care what you look like (unless you're "that" person wearing something totally ridiculous). Obviously there are lots of kids around, but if it's something you'd feel comfortable wearing to your local grocery store, it's fine. You certainly won't be the only one in leggings