Ester I love answering your questions! I have been on many of the tours and there hasn't been one that I didn't enjoy. I have learned about the dolphins at Living Seas, walked the Utilidors under the Magic Kingdom, and was eye to eye with a rhinoceros! Choosing the one that interests you the most is the hard part and enjoying it once you are there is the easy part!
My best advice is to read over all the options on the disney website,
www.disneyworld.com (search tours). One of the most popular is the Keys to the Kingdom tour which is a 5 hour tour of the Magic Kingdom. It is the one time you are able to see the magic
under a theme park! If you are espeically adventurous the segway tours are very popular as well. I think it is a great idea for you to enjoy something special while you are there. Call 407-WDW-TOUR (407-939-8687) to make reservations or inquire about the current tours during your vacation period. I can only imagine the stories you will be able to tell everyone at dinner.
I wasn't able to answer the question about the fireworks cruise as we are limited with space as well so please feel free to send another question about this and I will answer it as soon as possible. Your vacation is going to be spectacular with all the extras you are planning for yourself and for your family.