Do the fireworks shows always show at the same time? or if not when do the times get published so we can time our dining?
Illuminations is almost always at 9:00 pm. For major holidays they will have a show at 7:00 pm and then one later, usually closer to midnight.
Wishes is the tricky one. The time varies widely. I don't know when they set the schedule for that one. But I do know that they change it without notice.
Park hours and parades/fireworks schedules have been announced about six months out for the past couple of years. This year they were delayed quite a bit a couple of times--not sure why.
And Disney always reserves the right to change the schedules.