Hi, Jonathan! I've just gotten off of the phone with a cast member, and I'm so excited for this Frozen Summer experience! I can't wait to do it myself.
At the moment, there are not specific times available for the fireworks. You usually find the fireworks displays occurring at the end of the theme park day, which on the dates you've asked about is 10:00 PM. According to the cast member, more specific information will be available within the next several weeks.
According to the official
Disney Parks Blog Frozen Summer blog, the processional will take place twice daily. Again, times have not been announced yet, although I remember from last summer that there was a processional at around 11 AM. Check back as we get closer to the kick off dates, and I should be able to help you with more specific information.
I am really looking forward to cooling off with this Frozen treat this summer. Have a great time!