Since your little one loves Buzz Lightyear, remember to get a FastPass while you are there, so that you can go back and enjoy the ride a second time. It is the type of ride that you'll want to do twice (it has a laser-shooting game in it, and you all may want to try and beat your original scores).

I checked, and Stitch's Great Escape is NOT for a 3 year old, so don't bother there.

You've made great choices on the meal plans.

As far as the MK fireworks, we watched the Wishes show from the bridge spanning from Tomorrowland to the center court/castle area, and that was a great spot. If your little one still has stamina by the time the fireworks appear at 9 (occasionally 10p), I'd plan to see them from Fantasyland.....the view there is very good, and I've always found that, by that time of night, many of the little guys have petered out, or the parents want to head towards the park exit. That can work in your favor, because around 9, Fantasyland is empty, and you will once again be able to go on Dumbo/Pooh/Carousel/Teacups with no wait.

There is a spot where you can see the Lagoon light parade from the MK....head out of the park towards the Monorail entrance, and the light parade will be in front of you (you can hear the synthesizer music). The parade is a lot of fun. If you have extra nights, you can also view the lagoon light parade from the Polynesian or Grand Floridian.....go to the hotel as a guest (tell the parking attendant you are either going for dinner without a reservation, or just going to look the place over for future visits) and head out to the lagoon, and you'll have a great view without having to enter the parks. Check ahead of time to be sure of the viewing times for the parade, no matter where you plan to view it from. It moves in the water so the viewing time changes depending on your location.

If you are considering heading towards MGM, you might want to eat a meal at Pizza Planet. It's a replica of the restaurant from the Buzz Lightyear movie....it has good quality pizza and salads, and a game room complete with giant claw machine and other fun things to tire a 3 year old out.

There are also character greetings with Buzz and Woody in MGM so you may want to find the times for that, since your son is such a Buzz fan.

For Fantasmic, I suggest being at the gate one hour before the show starts. By 45 minutes before, the only seats left are at the far ends. Be prepared with soda and snacks as you will be in long, bleacher type seating (=backless) and you won't want to have to get up, as you will lose your spot. There are vendors walking through the stands, but I bought 2 sodas from them and paid $20, so come prepared (ok, the sodas had light-up ice cubes....did we really HAVE to have that???) You can get up and get refreshments in the stadium, as long as one of you stays behind in the seats. One Fantasmic starts, you will love it, and will forget about the long wait. And remember to hit the bathrooms before you get into your seats.

Will let you know if I can think of any more tips. Have fun!