Hi Deborah,
How exciting to take your son on his first visit to Walt Disney World! The tropical theme at
Disney's Caribbean Beach Resort is lovely, and you will be able to take advantage of all of the perks of staying at a Walt Disney World resort hotel!
As to the order that you visit the theme parks, you have some options. With very young children, I suggest that guests visit Magic Kingdom last, since that is what most children associate with Walt Disney World. With your son who is slightly older, perhaps his favorite will be Disney's Hollywood Studios, which has some more thrilling attractions, so you might save that for last. I would plan your first four days to spend one day at each of the four Walt Disney World theme parks. A good order might be Magic Kingdom, Disney's Animal Kingdom, Epcot, and last Disney's Hollywood Studios. For your last two days, you can decide together which parks to go back to, taking into account his favorite theme parks and theme parks where you did not have time to experience all of the attractions that you wanted to experience.
As to which attractions to use FastPass+ for, you will want to use those for the most popular attractions. Since you are staying at a Walt Disney World resort hotel, you will be able to plan these FastPass+ attractions using the My Disney Experience website. If you have not done so yet, visit
My Disney Experience to set up an account. You will need to attach your reservation number and have valid theme park admission. I suggest that you make your FastPass+ choices for the afternoon, since in the morning the theme parks are less crowded and lines are shorter.
I am limited in the space that I have to answer, Deborah. Please do write back if you have any further questions!