Hello, that's a great question!
I will give Magic Kingdom recommendations because I like them the most.
In my opinion, the perfect parade for them would be
Move It! Shake It! Dance & Play It! Street Party for a parade. Everyone is encouraged to move it, shake it, dance and play it throughout a 35 minute time of dancing and fun. With varying times throughout the day it's perfect for working around sleep schedules.
For fireworks it's a little more difficult to suggest as many young children don't like the loud sounds associated with fireworks, but I'll give it a shot.
There are two I would primarily suggest. The first is
Once Upon A Time, which is the shorter of the two at about 14 minutes, contains more characters they might recognize, and is earlier in the day for kids who are tired from a full day of fun.
The other is
Happily Ever After, this show runs about 18 minutes and is later at about 8PM.