Don't know about the fireworks timing, but if I remember right, there are no windows to look out of at CM. Whenever I've made ressies there, I've made them for 5-5:15 (right when they open). We've gotten in, the characters came around frequently and we ate our full before it got too crowded. Usually when we leave, there is a long line at the waiting area.
A coupple of times we even went back to MK after dinner to see the fireworks.
Terri