I would suggest you read as much as possible about the parks to familiarize yourself with what's new or changed. This website has tons of info, as does many others that can give detailed plans for visiting. Googling Disney tourist or touring plans, etc is a good start. Your 13 yr old guest might enjoy helping do the research for your trip.
Do not expect to do everything in 4 days, but choose what will appeal to your group. You might want to make a list of what attractions are a must-do at each park (like Pirates, Ex Everest, Soarin', Tower of Terror, etc) and those for
if the lines are short and you have time. Some rides always have long lines, such as Peter Pan, Toy Story Mania, and 7 Dwarf's Mine Train, so use fast passes for these. Meet and Greets take up a lot of time, so you might want to skip those. You might choose to devote only a morning to AK and HS in order to spend and more time at MK and Epcot.
Rushing through WDW is not the best way to go. Just enjoying the music, the sights, and the details is part of the whole magic, so trying to do
everything is going to create stress and possibly a ruined day.
As for dining reservations, the more popular places fill up fast, such as Akershus and Be Our Guest. Keep trying, particularly closer to your trip because people will reserve early, but change plans closer to the their trip. If you cannot get your first choice, there are plenty of other great places to eat. (Don't forget Sonny Eclipse at Cosmic Ray's!!)
Before going, be sure to put the WDW app on your smart phone so you can check wait times while there, and before you go to get an idea of what's popular, and bring a small battery back up and USB cord so your phone doesn't run out of juice. (Lipstick case sized ones are under $10 on Amazon.)