A couple of things...
- Joypolis is in Tokyo, not Osaka.
- I would not recommend going to FujiQ from Osaka, I doubt you could make it by opening which is VERY important. Go to Tokyo first, base there, then head out to Fuji.
- Japan school holidays don't start till the end of March, so you should be okay.
- The Magic passes at Universal are awesome, if it looks busy at all, grab one!
- The Disney days depend on how much you like Disney. First visit and you like Disney...absolutely three days.