You can certainly request it, whether or not you'll actually get it is another issue!
Tokyo Dining has some nice views if you are right at the window. Even being one row back (still very near) the window, we couldn't see a lot of the high up fireworks due to the roof overhang. They do pipe in the music. If you are right at the window you have a very nice view. Although due to the reflection of the window, its not perfect.
I love Illuminations and given the large area of the World Showcase never feel like I have to stake out a spot too far in advance to get a good view.
My favorite spots, that are easiest to get are between America and Morocco. You can see very well from the stairs that lead up to Tokyo Dining and can generally just walk right up there as the show begins. You aren't waterside but the view is very good. There is also an outdoor balocny in front of Tokyo Dining but I find the view on the side to be better. The waterside areas in the countries that you hit first (Mexico, Norway, Canada) all fill up first. People walk in and drop to the first spot they can. Keep walking further in and you'll find a better spot.